forked from cf-convention/cf-convention.github.io
-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathrequirements-recommendations-1.7.html
1357 lines (1356 loc) · 63.2 KB
/
requirements-recommendations-1.7.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<!--[if IE]><meta http-equiv="X-UA-Compatible" content="IE=edge"><![endif]-->
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="generator" content="Asciidoctor 1.5.6.1">
<title>CF Conformance Requirements and Recommendations 1.7</title>
<link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic%7CNoto+Serif:400,400italic,700,700italic%7CDroid+Sans+Mono:400,700">
<style>
/* Asciidoctor default stylesheet | MIT License | http://asciidoctor.org */
/* Remove comment around @import statement below when using as a custom stylesheet */
/*@import "https://fonts.googleapis.com/css?family=Open+Sans:300,300italic,400,400italic,600,600italic%7CNoto+Serif:400,400italic,700,700italic%7CDroid+Sans+Mono:400,700";*/
article,aside,details,figcaption,figure,footer,header,hgroup,main,nav,section,summary{display:block}
audio,canvas,video{display:inline-block}
audio:not([controls]){display:none;height:0}
[hidden],template{display:none}
script{display:none!important}
html{font-family:sans-serif;-ms-text-size-adjust:100%;-webkit-text-size-adjust:100%}
a{background:transparent}
a:focus{outline:thin dotted}
a:active,a:hover{outline:0}
h1{font-size:2em;margin:.67em 0}
abbr[title]{border-bottom:1px dotted}
b,strong{font-weight:bold}
dfn{font-style:italic}
hr{-moz-box-sizing:content-box;box-sizing:content-box;height:0}
mark{background:#ff0;color:#000}
code,kbd,pre,samp{font-family:monospace;font-size:1em}
pre{white-space:pre-wrap}
q{quotes:"\201C" "\201D" "\2018" "\2019"}
small{font-size:80%}
sub,sup{font-size:75%;line-height:0;position:relative;vertical-align:baseline}
sup{top:-.5em}
sub{bottom:-.25em}
img{border:0}
svg:not(:root){overflow:hidden}
figure{margin:0}
fieldset{border:1px solid silver;margin:0 2px;padding:.35em .625em .75em}
legend{border:0;padding:0}
button,input,select,textarea{font-family:inherit;font-size:100%;margin:0}
button,input{line-height:normal}
button,select{text-transform:none}
button,html input[type="button"],input[type="reset"],input[type="submit"]{-webkit-appearance:button;cursor:pointer}
button[disabled],html input[disabled]{cursor:default}
input[type="checkbox"],input[type="radio"]{box-sizing:border-box;padding:0}
input[type="search"]{-webkit-appearance:textfield;-moz-box-sizing:content-box;-webkit-box-sizing:content-box;box-sizing:content-box}
input[type="search"]::-webkit-search-cancel-button,input[type="search"]::-webkit-search-decoration{-webkit-appearance:none}
button::-moz-focus-inner,input::-moz-focus-inner{border:0;padding:0}
textarea{overflow:auto;vertical-align:top}
table{border-collapse:collapse;border-spacing:0}
*,*:before,*:after{-moz-box-sizing:border-box;-webkit-box-sizing:border-box;box-sizing:border-box}
html,body{font-size:100%}
body{background:#fff;color:rgba(0,0,0,.8);padding:0;margin:0;font-family:"Noto Serif","DejaVu Serif",serif;font-weight:400;font-style:normal;line-height:1;position:relative;cursor:auto;tab-size:4;-moz-osx-font-smoothing:grayscale;-webkit-font-smoothing:antialiased}
a:hover{cursor:pointer}
img,object,embed{max-width:100%;height:auto}
object,embed{height:100%}
img{-ms-interpolation-mode:bicubic}
.left{float:left!important}
.right{float:right!important}
.text-left{text-align:left!important}
.text-right{text-align:right!important}
.text-center{text-align:center!important}
.text-justify{text-align:justify!important}
.hide{display:none}
img,object,svg{display:inline-block;vertical-align:middle}
textarea{height:auto;min-height:50px}
select{width:100%}
.center{margin-left:auto;margin-right:auto}
.spread{width:100%}
p.lead,.paragraph.lead>p,#preamble>.sectionbody>.paragraph:first-of-type p{font-size:1.21875em;line-height:1.6}
.subheader,.admonitionblock td.content>.title,.audioblock>.title,.exampleblock>.title,.imageblock>.title,.listingblock>.title,.literalblock>.title,.stemblock>.title,.openblock>.title,.paragraph>.title,.quoteblock>.title,table.tableblock>.title,.verseblock>.title,.videoblock>.title,.dlist>.title,.olist>.title,.ulist>.title,.qlist>.title,.hdlist>.title{line-height:1.45;color:#7a2518;font-weight:400;margin-top:0;margin-bottom:.25em}
div,dl,dt,dd,ul,ol,li,h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6,pre,form,p,blockquote,th,td{margin:0;padding:0;direction:ltr}
a{color:#2156a5;text-decoration:underline;line-height:inherit}
a:hover,a:focus{color:#1d4b8f}
a img{border:none}
p{font-family:inherit;font-weight:400;font-size:1em;line-height:1.6;margin-bottom:1.25em;text-rendering:optimizeLegibility}
p aside{font-size:.875em;line-height:1.35;font-style:italic}
h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{font-family:"Open Sans","DejaVu Sans",sans-serif;font-weight:300;font-style:normal;color:#ba3925;text-rendering:optimizeLegibility;margin-top:1em;margin-bottom:.5em;line-height:1.0125em}
h1 small,h2 small,h3 small,#toctitle small,.sidebarblock>.content>.title small,h4 small,h5 small,h6 small{font-size:60%;color:#e99b8f;line-height:0}
h1{font-size:2.125em}
h2{font-size:1.6875em}
h3,#toctitle,.sidebarblock>.content>.title{font-size:1.375em}
h4,h5{font-size:1.125em}
h6{font-size:1em}
hr{border:solid #ddddd8;border-width:1px 0 0;clear:both;margin:1.25em 0 1.1875em;height:0}
em,i{font-style:italic;line-height:inherit}
strong,b{font-weight:bold;line-height:inherit}
small{font-size:60%;line-height:inherit}
code{font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;font-weight:400;color:rgba(0,0,0,.9)}
ul,ol,dl{font-size:1em;line-height:1.6;margin-bottom:1.25em;list-style-position:outside;font-family:inherit}
ul,ol{margin-left:1.5em}
ul li ul,ul li ol{margin-left:1.25em;margin-bottom:0;font-size:1em}
ul.square li ul,ul.circle li ul,ul.disc li ul{list-style:inherit}
ul.square{list-style-type:square}
ul.circle{list-style-type:circle}
ul.disc{list-style-type:disc}
ol li ul,ol li ol{margin-left:1.25em;margin-bottom:0}
dl dt{margin-bottom:.3125em;font-weight:bold}
dl dd{margin-bottom:1.25em}
abbr,acronym{text-transform:uppercase;font-size:90%;color:rgba(0,0,0,.8);border-bottom:1px dotted #ddd;cursor:help}
abbr{text-transform:none}
blockquote{margin:0 0 1.25em;padding:.5625em 1.25em 0 1.1875em;border-left:1px solid #ddd}
blockquote cite{display:block;font-size:.9375em;color:rgba(0,0,0,.6)}
blockquote cite:before{content:"\2014 \0020"}
blockquote cite a,blockquote cite a:visited{color:rgba(0,0,0,.6)}
blockquote,blockquote p{line-height:1.6;color:rgba(0,0,0,.85)}
@media only screen and (min-width:768px){h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{line-height:1.2}
h1{font-size:2.75em}
h2{font-size:2.3125em}
h3,#toctitle,.sidebarblock>.content>.title{font-size:1.6875em}
h4{font-size:1.4375em}}
table{background:#fff;margin-bottom:1.25em;border:solid 1px #dedede}
table thead,table tfoot{background:#f7f8f7;font-weight:bold}
table thead tr th,table thead tr td,table tfoot tr th,table tfoot tr td{padding:.5em .625em .625em;font-size:inherit;color:rgba(0,0,0,.8);text-align:left}
table tr th,table tr td{padding:.5625em .625em;font-size:inherit;color:rgba(0,0,0,.8)}
table tr.even,table tr.alt,table tr:nth-of-type(even){background:#f8f8f7}
table thead tr th,table tfoot tr th,table tbody tr td,table tr td,table tfoot tr td{display:table-cell;line-height:1.6}
h1,h2,h3,#toctitle,.sidebarblock>.content>.title,h4,h5,h6{line-height:1.2;word-spacing:-.05em}
h1 strong,h2 strong,h3 strong,#toctitle strong,.sidebarblock>.content>.title strong,h4 strong,h5 strong,h6 strong{font-weight:400}
.clearfix:before,.clearfix:after,.float-group:before,.float-group:after{content:" ";display:table}
.clearfix:after,.float-group:after{clear:both}
*:not(pre)>code{font-size:.9375em;font-style:normal!important;letter-spacing:0;padding:.1em .5ex;word-spacing:-.15em;background-color:#f7f7f8;-webkit-border-radius:4px;border-radius:4px;line-height:1.45;text-rendering:optimizeSpeed;word-wrap:break-word}
*:not(pre)>code.nobreak{word-wrap:normal}
*:not(pre)>code.nowrap{white-space:nowrap}
pre,pre>code{line-height:1.45;color:rgba(0,0,0,.9);font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;font-weight:400;text-rendering:optimizeSpeed}
em em{font-style:normal}
strong strong{font-weight:400}
.keyseq{color:rgba(51,51,51,.8)}
kbd{font-family:"Droid Sans Mono","DejaVu Sans Mono",monospace;display:inline-block;color:rgba(0,0,0,.8);font-size:.65em;line-height:1.45;background-color:#f7f7f7;border:1px solid #ccc;-webkit-border-radius:3px;border-radius:3px;-webkit-box-shadow:0 1px 0 rgba(0,0,0,.2),0 0 0 .1em white inset;box-shadow:0 1px 0 rgba(0,0,0,.2),0 0 0 .1em #fff inset;margin:0 .15em;padding:.2em .5em;vertical-align:middle;position:relative;top:-.1em;white-space:nowrap}
.keyseq kbd:first-child{margin-left:0}
.keyseq kbd:last-child{margin-right:0}
.menuseq,.menuref{color:#000}
.menuseq b:not(.caret),.menuref{font-weight:inherit}
.menuseq{word-spacing:-.02em}
.menuseq b.caret{font-size:1.25em;line-height:.8}
.menuseq i.caret{font-weight:bold;text-align:center;width:.45em}
b.button:before,b.button:after{position:relative;top:-1px;font-weight:400}
b.button:before{content:"[";padding:0 3px 0 2px}
b.button:after{content:"]";padding:0 2px 0 3px}
p a>code:hover{color:rgba(0,0,0,.9)}
#header,#content,#footnotes,#footer{width:100%;margin-left:auto;margin-right:auto;margin-top:0;margin-bottom:0;max-width:62.5em;*zoom:1;position:relative;padding-left:.9375em;padding-right:.9375em}
#header:before,#header:after,#content:before,#content:after,#footnotes:before,#footnotes:after,#footer:before,#footer:after{content:" ";display:table}
#header:after,#content:after,#footnotes:after,#footer:after{clear:both}
#content{margin-top:1.25em}
#content:before{content:none}
#header>h1:first-child{color:rgba(0,0,0,.85);margin-top:2.25rem;margin-bottom:0}
#header>h1:first-child+#toc{margin-top:8px;border-top:1px solid #ddddd8}
#header>h1:only-child,body.toc2 #header>h1:nth-last-child(2){border-bottom:1px solid #ddddd8;padding-bottom:8px}
#header .details{border-bottom:1px solid #ddddd8;line-height:1.45;padding-top:.25em;padding-bottom:.25em;padding-left:.25em;color:rgba(0,0,0,.6);display:-ms-flexbox;display:-webkit-flex;display:flex;-ms-flex-flow:row wrap;-webkit-flex-flow:row wrap;flex-flow:row wrap}
#header .details span:first-child{margin-left:-.125em}
#header .details span.email a{color:rgba(0,0,0,.85)}
#header .details br{display:none}
#header .details br+span:before{content:"\00a0\2013\00a0"}
#header .details br+span.author:before{content:"\00a0\22c5\00a0";color:rgba(0,0,0,.85)}
#header .details br+span#revremark:before{content:"\00a0|\00a0"}
#header #revnumber{text-transform:capitalize}
#header #revnumber:after{content:"\00a0"}
#content>h1:first-child:not([class]){color:rgba(0,0,0,.85);border-bottom:1px solid #ddddd8;padding-bottom:8px;margin-top:0;padding-top:1rem;margin-bottom:1.25rem}
#toc{border-bottom:1px solid #efefed;padding-bottom:.5em}
#toc>ul{margin-left:.125em}
#toc ul.sectlevel0>li>a{font-style:italic}
#toc ul.sectlevel0 ul.sectlevel1{margin:.5em 0}
#toc ul{font-family:"Open Sans","DejaVu Sans",sans-serif;list-style-type:none}
#toc li{line-height:1.3334;margin-top:.3334em}
#toc a{text-decoration:none}
#toc a:active{text-decoration:underline}
#toctitle{color:#7a2518;font-size:1.2em}
@media only screen and (min-width:768px){#toctitle{font-size:1.375em}
body.toc2{padding-left:15em;padding-right:0}
#toc.toc2{margin-top:0!important;background-color:#f8f8f7;position:fixed;width:15em;left:0;top:0;border-right:1px solid #efefed;border-top-width:0!important;border-bottom-width:0!important;z-index:1000;padding:1.25em 1em;height:100%;overflow:auto}
#toc.toc2 #toctitle{margin-top:0;margin-bottom:.8rem;font-size:1.2em}
#toc.toc2>ul{font-size:.9em;margin-bottom:0}
#toc.toc2 ul ul{margin-left:0;padding-left:1em}
#toc.toc2 ul.sectlevel0 ul.sectlevel1{padding-left:0;margin-top:.5em;margin-bottom:.5em}
body.toc2.toc-right{padding-left:0;padding-right:15em}
body.toc2.toc-right #toc.toc2{border-right-width:0;border-left:1px solid #efefed;left:auto;right:0}}
@media only screen and (min-width:1280px){body.toc2{padding-left:20em;padding-right:0}
#toc.toc2{width:20em}
#toc.toc2 #toctitle{font-size:1.375em}
#toc.toc2>ul{font-size:.95em}
#toc.toc2 ul ul{padding-left:1.25em}
body.toc2.toc-right{padding-left:0;padding-right:20em}}
#content #toc{border-style:solid;border-width:1px;border-color:#e0e0dc;margin-bottom:1.25em;padding:1.25em;background:#f8f8f7;-webkit-border-radius:4px;border-radius:4px}
#content #toc>:first-child{margin-top:0}
#content #toc>:last-child{margin-bottom:0}
#footer{max-width:100%;background-color:rgba(0,0,0,.8);padding:1.25em}
#footer-text{color:rgba(255,255,255,.8);line-height:1.44}
.sect1{padding-bottom:.625em}
@media only screen and (min-width:768px){.sect1{padding-bottom:1.25em}}
.sect1+.sect1{border-top:1px solid #efefed}
#content h1>a.anchor,h2>a.anchor,h3>a.anchor,#toctitle>a.anchor,.sidebarblock>.content>.title>a.anchor,h4>a.anchor,h5>a.anchor,h6>a.anchor{position:absolute;z-index:1001;width:1.5ex;margin-left:-1.5ex;display:block;text-decoration:none!important;visibility:hidden;text-align:center;font-weight:400}
#content h1>a.anchor:before,h2>a.anchor:before,h3>a.anchor:before,#toctitle>a.anchor:before,.sidebarblock>.content>.title>a.anchor:before,h4>a.anchor:before,h5>a.anchor:before,h6>a.anchor:before{content:"\00A7";font-size:.85em;display:block;padding-top:.1em}
#content h1:hover>a.anchor,#content h1>a.anchor:hover,h2:hover>a.anchor,h2>a.anchor:hover,h3:hover>a.anchor,#toctitle:hover>a.anchor,.sidebarblock>.content>.title:hover>a.anchor,h3>a.anchor:hover,#toctitle>a.anchor:hover,.sidebarblock>.content>.title>a.anchor:hover,h4:hover>a.anchor,h4>a.anchor:hover,h5:hover>a.anchor,h5>a.anchor:hover,h6:hover>a.anchor,h6>a.anchor:hover{visibility:visible}
#content h1>a.link,h2>a.link,h3>a.link,#toctitle>a.link,.sidebarblock>.content>.title>a.link,h4>a.link,h5>a.link,h6>a.link{color:#ba3925;text-decoration:none}
#content h1>a.link:hover,h2>a.link:hover,h3>a.link:hover,#toctitle>a.link:hover,.sidebarblock>.content>.title>a.link:hover,h4>a.link:hover,h5>a.link:hover,h6>a.link:hover{color:#a53221}
.audioblock,.imageblock,.literalblock,.listingblock,.stemblock,.videoblock{margin-bottom:1.25em}
.admonitionblock td.content>.title,.audioblock>.title,.exampleblock>.title,.imageblock>.title,.listingblock>.title,.literalblock>.title,.stemblock>.title,.openblock>.title,.paragraph>.title,.quoteblock>.title,table.tableblock>.title,.verseblock>.title,.videoblock>.title,.dlist>.title,.olist>.title,.ulist>.title,.qlist>.title,.hdlist>.title{text-rendering:optimizeLegibility;text-align:left;font-family:"Noto Serif","DejaVu Serif",serif;font-size:1rem;font-style:italic}
table.tableblock>caption.title{white-space:nowrap;overflow:visible;max-width:0}
.paragraph.lead>p,#preamble>.sectionbody>.paragraph:first-of-type p{color:rgba(0,0,0,.85)}
table.tableblock #preamble>.sectionbody>.paragraph:first-of-type p{font-size:inherit}
.admonitionblock>table{border-collapse:separate;border:0;background:none;width:100%}
.admonitionblock>table td.icon{text-align:center;width:80px}
.admonitionblock>table td.icon img{max-width:initial}
.admonitionblock>table td.icon .title{font-weight:bold;font-family:"Open Sans","DejaVu Sans",sans-serif;text-transform:uppercase}
.admonitionblock>table td.content{padding-left:1.125em;padding-right:1.25em;border-left:1px solid #ddddd8;color:rgba(0,0,0,.6)}
.admonitionblock>table td.content>:last-child>:last-child{margin-bottom:0}
.exampleblock>.content{border-style:solid;border-width:1px;border-color:#e6e6e6;margin-bottom:1.25em;padding:1.25em;background:#fff;-webkit-border-radius:4px;border-radius:4px}
.exampleblock>.content>:first-child{margin-top:0}
.exampleblock>.content>:last-child{margin-bottom:0}
.sidebarblock{border-style:solid;border-width:1px;border-color:#e0e0dc;margin-bottom:1.25em;padding:1.25em;background:#f8f8f7;-webkit-border-radius:4px;border-radius:4px}
.sidebarblock>:first-child{margin-top:0}
.sidebarblock>:last-child{margin-bottom:0}
.sidebarblock>.content>.title{color:#7a2518;margin-top:0;text-align:center}
.exampleblock>.content>:last-child>:last-child,.exampleblock>.content .olist>ol>li:last-child>:last-child,.exampleblock>.content .ulist>ul>li:last-child>:last-child,.exampleblock>.content .qlist>ol>li:last-child>:last-child,.sidebarblock>.content>:last-child>:last-child,.sidebarblock>.content .olist>ol>li:last-child>:last-child,.sidebarblock>.content .ulist>ul>li:last-child>:last-child,.sidebarblock>.content .qlist>ol>li:last-child>:last-child{margin-bottom:0}
.literalblock pre,.listingblock pre:not(.highlight),.listingblock pre[class="highlight"],.listingblock pre[class^="highlight "],.listingblock pre.CodeRay,.listingblock pre.prettyprint{background:#f7f7f8}
.sidebarblock .literalblock pre,.sidebarblock .listingblock pre:not(.highlight),.sidebarblock .listingblock pre[class="highlight"],.sidebarblock .listingblock pre[class^="highlight "],.sidebarblock .listingblock pre.CodeRay,.sidebarblock .listingblock pre.prettyprint{background:#f2f1f1}
.literalblock pre,.literalblock pre[class],.listingblock pre,.listingblock pre[class]{-webkit-border-radius:4px;border-radius:4px;word-wrap:break-word;padding:1em;font-size:.8125em}
.literalblock pre.nowrap,.literalblock pre[class].nowrap,.listingblock pre.nowrap,.listingblock pre[class].nowrap{overflow-x:auto;white-space:pre;word-wrap:normal}
@media only screen and (min-width:768px){.literalblock pre,.literalblock pre[class],.listingblock pre,.listingblock pre[class]{font-size:.90625em}}
@media only screen and (min-width:1280px){.literalblock pre,.literalblock pre[class],.listingblock pre,.listingblock pre[class]{font-size:1em}}
.literalblock.output pre{color:#f7f7f8;background-color:rgba(0,0,0,.9)}
.listingblock pre.highlightjs{padding:0}
.listingblock pre.highlightjs>code{padding:1em;-webkit-border-radius:4px;border-radius:4px}
.listingblock pre.prettyprint{border-width:0}
.listingblock>.content{position:relative}
.listingblock code[data-lang]:before{display:none;content:attr(data-lang);position:absolute;font-size:.75em;top:.425rem;right:.5rem;line-height:1;text-transform:uppercase;color:#999}
.listingblock:hover code[data-lang]:before{display:block}
.listingblock.terminal pre .command:before{content:attr(data-prompt);padding-right:.5em;color:#999}
.listingblock.terminal pre .command:not([data-prompt]):before{content:"$"}
table.pyhltable{border-collapse:separate;border:0;margin-bottom:0;background:none}
table.pyhltable td{vertical-align:top;padding-top:0;padding-bottom:0;line-height:1.45}
table.pyhltable td.code{padding-left:.75em;padding-right:0}
pre.pygments .lineno,table.pyhltable td:not(.code){color:#999;padding-left:0;padding-right:.5em;border-right:1px solid #ddddd8}
pre.pygments .lineno{display:inline-block;margin-right:.25em}
table.pyhltable .linenodiv{background:none!important;padding-right:0!important}
.quoteblock{margin:0 1em 1.25em 1.5em;display:table}
.quoteblock>.title{margin-left:-1.5em;margin-bottom:.75em}
.quoteblock blockquote,.quoteblock blockquote p{color:rgba(0,0,0,.85);font-size:1.15rem;line-height:1.75;word-spacing:.1em;letter-spacing:0;font-style:italic;text-align:justify}
.quoteblock blockquote{margin:0;padding:0;border:0}
.quoteblock blockquote:before{content:"\201c";float:left;font-size:2.75em;font-weight:bold;line-height:.6em;margin-left:-.6em;color:#7a2518;text-shadow:0 1px 2px rgba(0,0,0,.1)}
.quoteblock blockquote>.paragraph:last-child p{margin-bottom:0}
.quoteblock .attribution{margin-top:.5em;margin-right:.5ex;text-align:right}
.quoteblock .quoteblock{margin-left:0;margin-right:0;padding:.5em 0;border-left:3px solid rgba(0,0,0,.6)}
.quoteblock .quoteblock blockquote{padding:0 0 0 .75em}
.quoteblock .quoteblock blockquote:before{display:none}
.verseblock{margin:0 1em 1.25em 1em}
.verseblock pre{font-family:"Open Sans","DejaVu Sans",sans;font-size:1.15rem;color:rgba(0,0,0,.85);font-weight:300;text-rendering:optimizeLegibility}
.verseblock pre strong{font-weight:400}
.verseblock .attribution{margin-top:1.25rem;margin-left:.5ex}
.quoteblock .attribution,.verseblock .attribution{font-size:.9375em;line-height:1.45;font-style:italic}
.quoteblock .attribution br,.verseblock .attribution br{display:none}
.quoteblock .attribution cite,.verseblock .attribution cite{display:block;letter-spacing:-.025em;color:rgba(0,0,0,.6)}
.quoteblock.abstract{margin:0 0 1.25em 0;display:block}
.quoteblock.abstract blockquote,.quoteblock.abstract blockquote p{text-align:left;word-spacing:0}
.quoteblock.abstract blockquote:before,.quoteblock.abstract blockquote p:first-of-type:before{display:none}
table.tableblock{max-width:100%;border-collapse:separate}
table.tableblock td>.paragraph:last-child p>p:last-child,table.tableblock th>p:last-child,table.tableblock td>p:last-child{margin-bottom:0}
table.tableblock,th.tableblock,td.tableblock{border:0 solid #dedede}
table.grid-all>thead>tr>.tableblock,table.grid-all>tbody>tr>.tableblock{border-width:0 1px 1px 0}
table.grid-all>tfoot>tr>.tableblock{border-width:1px 1px 0 0}
table.grid-cols>*>tr>.tableblock{border-width:0 1px 0 0}
table.grid-rows>thead>tr>.tableblock,table.grid-rows>tbody>tr>.tableblock{border-width:0 0 1px 0}
table.grid-rows>tfoot>tr>.tableblock{border-width:1px 0 0 0}
table.grid-all>*>tr>.tableblock:last-child,table.grid-cols>*>tr>.tableblock:last-child{border-right-width:0}
table.grid-all>tbody>tr:last-child>.tableblock,table.grid-all>thead:last-child>tr>.tableblock,table.grid-rows>tbody>tr:last-child>.tableblock,table.grid-rows>thead:last-child>tr>.tableblock{border-bottom-width:0}
table.frame-all{border-width:1px}
table.frame-sides{border-width:0 1px}
table.frame-topbot{border-width:1px 0}
th.halign-left,td.halign-left{text-align:left}
th.halign-right,td.halign-right{text-align:right}
th.halign-center,td.halign-center{text-align:center}
th.valign-top,td.valign-top{vertical-align:top}
th.valign-bottom,td.valign-bottom{vertical-align:bottom}
th.valign-middle,td.valign-middle{vertical-align:middle}
table thead th,table tfoot th{font-weight:bold}
tbody tr th{display:table-cell;line-height:1.6;background:#f7f8f7}
tbody tr th,tbody tr th p,tfoot tr th,tfoot tr th p{color:rgba(0,0,0,.8);font-weight:bold}
p.tableblock>code:only-child{background:none;padding:0}
p.tableblock{font-size:1em}
td>div.verse{white-space:pre}
ol{margin-left:1.75em}
ul li ol{margin-left:1.5em}
dl dd{margin-left:1.125em}
dl dd:last-child,dl dd:last-child>:last-child{margin-bottom:0}
ol>li p,ul>li p,ul dd,ol dd,.olist .olist,.ulist .ulist,.ulist .olist,.olist .ulist{margin-bottom:.625em}
ul.checklist,ul.none,ol.none,ul.no-bullet,ol.no-bullet,ol.unnumbered,ul.unstyled,ol.unstyled{list-style-type:none}
ul.no-bullet,ol.no-bullet,ol.unnumbered{margin-left:.625em}
ul.unstyled,ol.unstyled{margin-left:0}
ul.checklist{margin-left:.625em}
ul.checklist li>p:first-child>.fa-square-o:first-child,ul.checklist li>p:first-child>.fa-check-square-o:first-child{width:1.25em;font-size:.8em;position:relative;bottom:.125em}
ul.checklist li>p:first-child>input[type="checkbox"]:first-child{margin-right:.25em}
ul.inline{margin:0 auto .625em auto;margin-left:-1.375em;margin-right:0;padding:0;list-style:none;overflow:hidden}
ul.inline>li{list-style:none;float:left;margin-left:1.375em;display:block}
ul.inline>li>*{display:block}
.unstyled dl dt{font-weight:400;font-style:normal}
ol.arabic{list-style-type:decimal}
ol.decimal{list-style-type:decimal-leading-zero}
ol.loweralpha{list-style-type:lower-alpha}
ol.upperalpha{list-style-type:upper-alpha}
ol.lowerroman{list-style-type:lower-roman}
ol.upperroman{list-style-type:upper-roman}
ol.lowergreek{list-style-type:lower-greek}
.hdlist>table,.colist>table{border:0;background:none}
.hdlist>table>tbody>tr,.colist>table>tbody>tr{background:none}
td.hdlist1,td.hdlist2{vertical-align:top;padding:0 .625em}
td.hdlist1{font-weight:bold;padding-bottom:1.25em}
.literalblock+.colist,.listingblock+.colist{margin-top:-.5em}
.colist>table tr>td:first-of-type{padding:.4em .75em 0 .75em;line-height:1;vertical-align:top}
.colist>table tr>td:first-of-type img{max-width:initial}
.colist>table tr>td:last-of-type{padding:.25em 0}
.thumb,.th{line-height:0;display:inline-block;border:solid 4px #fff;-webkit-box-shadow:0 0 0 1px #ddd;box-shadow:0 0 0 1px #ddd}
.imageblock.left,.imageblock[style*="float: left"]{margin:.25em .625em 1.25em 0}
.imageblock.right,.imageblock[style*="float: right"]{margin:.25em 0 1.25em .625em}
.imageblock>.title{margin-bottom:0}
.imageblock.thumb,.imageblock.th{border-width:6px}
.imageblock.thumb>.title,.imageblock.th>.title{padding:0 .125em}
.image.left,.image.right{margin-top:.25em;margin-bottom:.25em;display:inline-block;line-height:0}
.image.left{margin-right:.625em}
.image.right{margin-left:.625em}
a.image{text-decoration:none;display:inline-block}
a.image object{pointer-events:none}
sup.footnote,sup.footnoteref{font-size:.875em;position:static;vertical-align:super}
sup.footnote a,sup.footnoteref a{text-decoration:none}
sup.footnote a:active,sup.footnoteref a:active{text-decoration:underline}
#footnotes{padding-top:.75em;padding-bottom:.75em;margin-bottom:.625em}
#footnotes hr{width:20%;min-width:6.25em;margin:-.25em 0 .75em 0;border-width:1px 0 0 0}
#footnotes .footnote{padding:0 .375em 0 .225em;line-height:1.3334;font-size:.875em;margin-left:1.2em;text-indent:-1.05em;margin-bottom:.2em}
#footnotes .footnote a:first-of-type{font-weight:bold;text-decoration:none}
#footnotes .footnote:last-of-type{margin-bottom:0}
#content #footnotes{margin-top:-.625em;margin-bottom:0;padding:.75em 0}
.gist .file-data>table{border:0;background:#fff;width:100%;margin-bottom:0}
.gist .file-data>table td.line-data{width:99%}
div.unbreakable{page-break-inside:avoid}
.big{font-size:larger}
.small{font-size:smaller}
.underline{text-decoration:underline}
.overline{text-decoration:overline}
.line-through{text-decoration:line-through}
.aqua{color:#00bfbf}
.aqua-background{background-color:#00fafa}
.black{color:#000}
.black-background{background-color:#000}
.blue{color:#0000bf}
.blue-background{background-color:#0000fa}
.fuchsia{color:#bf00bf}
.fuchsia-background{background-color:#fa00fa}
.gray{color:#606060}
.gray-background{background-color:#7d7d7d}
.green{color:#006000}
.green-background{background-color:#007d00}
.lime{color:#00bf00}
.lime-background{background-color:#00fa00}
.maroon{color:#600000}
.maroon-background{background-color:#7d0000}
.navy{color:#000060}
.navy-background{background-color:#00007d}
.olive{color:#606000}
.olive-background{background-color:#7d7d00}
.purple{color:#600060}
.purple-background{background-color:#7d007d}
.red{color:#bf0000}
.red-background{background-color:#fa0000}
.silver{color:#909090}
.silver-background{background-color:#bcbcbc}
.teal{color:#006060}
.teal-background{background-color:#007d7d}
.white{color:#bfbfbf}
.white-background{background-color:#fafafa}
.yellow{color:#bfbf00}
.yellow-background{background-color:#fafa00}
span.icon>.fa{cursor:default}
a span.icon>.fa{cursor:inherit}
.admonitionblock td.icon [class^="fa icon-"]{font-size:2.5em;text-shadow:1px 1px 2px rgba(0,0,0,.5);cursor:default}
.admonitionblock td.icon .icon-note:before{content:"\f05a";color:#19407c}
.admonitionblock td.icon .icon-tip:before{content:"\f0eb";text-shadow:1px 1px 2px rgba(155,155,0,.8);color:#111}
.admonitionblock td.icon .icon-warning:before{content:"\f071";color:#bf6900}
.admonitionblock td.icon .icon-caution:before{content:"\f06d";color:#bf3400}
.admonitionblock td.icon .icon-important:before{content:"\f06a";color:#bf0000}
.conum[data-value]{display:inline-block;color:#fff!important;background-color:rgba(0,0,0,.8);-webkit-border-radius:100px;border-radius:100px;text-align:center;font-size:.75em;width:1.67em;height:1.67em;line-height:1.67em;font-family:"Open Sans","DejaVu Sans",sans-serif;font-style:normal;font-weight:bold}
.conum[data-value] *{color:#fff!important}
.conum[data-value]+b{display:none}
.conum[data-value]:after{content:attr(data-value)}
pre .conum[data-value]{position:relative;top:-.125em}
b.conum *{color:inherit!important}
.conum:not([data-value]):empty{display:none}
dt,th.tableblock,td.content,div.footnote{text-rendering:optimizeLegibility}
h1,h2,p,td.content,span.alt{letter-spacing:-.01em}
p strong,td.content strong,div.footnote strong{letter-spacing:-.005em}
p,blockquote,dt,td.content,span.alt{font-size:1.0625rem}
p{margin-bottom:1.25rem}
.sidebarblock p,.sidebarblock dt,.sidebarblock td.content,p.tableblock{font-size:1em}
.exampleblock>.content{background-color:#fffef7;border-color:#e0e0dc;-webkit-box-shadow:0 1px 4px #e0e0dc;box-shadow:0 1px 4px #e0e0dc}
.print-only{display:none!important}
@media print{@page{margin:1.25cm .75cm}
*{-webkit-box-shadow:none!important;box-shadow:none!important;text-shadow:none!important}
a{color:inherit!important;text-decoration:underline!important}
a.bare,a[href^="#"],a[href^="mailto:"]{text-decoration:none!important}
a[href^="http:"]:not(.bare):after,a[href^="https:"]:not(.bare):after{content:"(" attr(href) ")";display:inline-block;font-size:.875em;padding-left:.25em}
abbr[title]:after{content:" (" attr(title) ")"}
pre,blockquote,tr,img,object,svg{page-break-inside:avoid}
thead{display:table-header-group}
svg{max-width:100%}
p,blockquote,dt,td.content{font-size:1em;orphans:3;widows:3}
h2,h3,#toctitle,.sidebarblock>.content>.title{page-break-after:avoid}
#toc,.sidebarblock,.exampleblock>.content{background:none!important}
#toc{border-bottom:1px solid #ddddd8!important;padding-bottom:0!important}
.sect1{padding-bottom:0!important}
.sect1+.sect1{border:0!important}
#header>h1:first-child{margin-top:1.25rem}
body.book #header{text-align:center}
body.book #header>h1:first-child{border:0!important;margin:2.5em 0 1em 0}
body.book #header .details{border:0!important;display:block;padding:0!important}
body.book #header .details span:first-child{margin-left:0!important}
body.book #header .details br{display:block}
body.book #header .details br+span:before{content:none!important}
body.book #toc{border:0!important;text-align:left!important;padding:0!important;margin:0!important}
body.book #toc,body.book #preamble,body.book h1.sect0,body.book .sect1>h2{page-break-before:always}
.listingblock code[data-lang]:before{display:block}
#footer{background:none!important;padding:0 .9375em}
#footer-text{color:rgba(0,0,0,.6)!important;font-size:.9em}
.hide-on-print{display:none!important}
.print-only{display:block!important}
.hide-for-print{display:none!important}
.show-for-print{display:inherit!important}}
</style>
</head>
<body class="article">
<div id="header">
</div>
<div id="content">
<div class="sect1">
<h2 id="cf-conformance-requirements-and-recommendations-1.7">CF Conformance Requirements and Recommendations 1.7</h2>
<div class="sectionbody">
<div class="ulist">
<ul>
<li>
<p>The following is a list of requirements and recommendations for a CF
conforming netCDF file. They are organized by the section of the CF
document that they pertain to.</p>
</li>
<li>
<p>This document is intended to be a concise summary of the
<a href="http://cfconventions.org/cf-conventions/cf-conventions.html">CF Conventions document</a>.
If there are any discrepencies between the two, the
conventions document is the ultimate authority.</p>
</li>
<li>
<p>This document will updated as required to correct mistakes or add new
material required for completeness or clarity.</p>
</li>
</ul>
</div>
<div class="sect2">
<h3 id="filename">2.1 Filename</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>Filename must have ".nc" suffix.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="data-types">2.2 Data Types</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>CF attributes that take string values must be 1D character arrays.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="naming-conventions">2.3 Naming Conventions</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>Variable, dimension and attribute names must begin with a letter and
be composed of letters, digits, and underscores.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>No two variable names should be identical when case is ignored.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="dimensions">2.4 Dimensions</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The dimensions of a variable must all have different names.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>If any or all of the dimensions of a variable have the interpretations
(as given by their units or axis attribute) of time (T), height or depth
(Z), latitude (Y), or longitude (X) then those dimensions should appear
in the relative order T, then Z, then Y, then X in the CDL definition
corresponding to the file.</p>
</li>
<li>
<p>In files that are meant to conform to the COARDS subset of CF, any
dimensions of a variable other than space and time dimensions should be
added "to the left" of the space and time dimensions as represented in
CDL.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="missing-data-valid-and-actual-range-of-data">2.5.1 Missing data, valid and actual range of data</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>valid_range</code></strong> attribute must not be present if the <strong><code>valid_min</code></strong> and/or
<strong><code>valid_max</code></strong> attributes are present.</p>
</li>
<li>
<p>The <strong><code>_FillValue</code></strong> attribute must be the same type as its associated
variable.</p>
</li>
<li>
<p>The <strong><code>missing_value</code></strong> attribute must be the same type as its associated
variable.</p>
</li>
<li>
<p>The <strong><code>actual_range</code></strong> attribute must be of the same type as its associated
variable unless there is a <strong><code>scale_factor</code></strong> and/or <strong><code>add_offset</code></strong> attribute, in
which case it must be of the same type as those attributes.</p>
</li>
<li>
<p>The <strong><code>actual_range</code></strong> attribute must have two elements, of which the first
exactly equals the minimum non-missing value occurring in the associated
variable after any <strong><code>scale_factor</code></strong> and <strong><code>add_offset</code></strong> are applied, and the
second exactly equals the maximum value in the same way.</p>
</li>
<li>
<p>There must not be an <strong><code>actual_range</code></strong> attribute if all the data values of
the associated variable equal the missing value.</p>
</li>
<li>
<p>If both the <strong><code>actual_range</code></strong> and <strong><code>valid_range/valid_min/valid_max</code></strong> are
specified, the values of the <strong><code>actual_range</code></strong> must be valid values.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The value of the <strong><code>_FillValue</code></strong> attribute should not be within a specified
valid range.</p>
</li>
<li>
<p>If both <strong><code>missing_value</code></strong> and <strong><code>_FillValue</code></strong> be used, they should have the
same value.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="identification-of-conventions">2.6.1 Identification of Conventions</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>Files that conform to the CF version 1.7 conventions must indicate
this by setting the global <strong><code>Conventions</code></strong> attribute to the string value
"CF-1.7".</p>
</li>
<li>
<p>The <strong><code>Conventions</code></strong> attribute may be a single text string containing a list
of convention names separated by blank space or commas, one of which shall
be the full CF string as described above.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="description-of-file-contents">2.6.2 Description of File Contents</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>title</code></strong>, <strong><code>history</code></strong>, <strong><code>institution</code></strong>, <strong><code>source</code></strong>, <strong><code>references</code></strong>, and <strong><code>comment</code></strong>
attributes are all type string.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>title</code></strong> and <strong><code>history</code></strong> attributes are only defined as global
attributes. If they are used as per variable attributes a CF compliant
application should treat them exactly as it would treat any other
unrecognized attribute.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="_2_6_3_external_variables">2.6.3 External variables</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>external_variables</code></strong> attribute is of string type and contains a blank-separated
list of variable names.</p>
</li>
<li>
<p>No variable named by <strong><code>external_variables</code></strong> is allowed in the file.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="description-of-the-data">3 Description of the Data</h3>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>All variables should use either the <strong><code>long_name</code></strong> or the <strong><code>standard_name</code></strong>
attributes to describe their contents. Exceptions are boundary and
climatology variables.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="units">3.1 Units</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>units</code></strong> attribute is required for all variables that represent
dimensional quantities (except for boundary variables defined in
<a href="http://cfconventions.org/cf-conventions/cf-conventions.html#cell-boundaries">section 7.1</a>
and climatology variables defined in
<a href="http://cfconventions.org/cf-conventions/cf-conventions.html#climatological-statistics">section 7.4</a>
).</p>
</li>
<li>
<p>The type of the <strong><code>units</code></strong> attribute is a string that must be recognizable
by the udunits package. Exceptions are the units <strong><code>level, layer, and
sigma_level</code></strong>.</p>
</li>
<li>
<p>The <strong><code>units</code></strong> of a variable that specifies a <strong><code>standard_name</code></strong> must be
physically equivalent to the canonical units given in the standard name
table, as modified by the <strong><code>standard_name</code></strong> modifier, if there is one,
according to Appendix C, and then modified by all the methods listed in
order by the <strong><code>cell_methods</code></strong> attribute, if one is present, according to
Appendix E.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The units <strong><code>level</code></strong>, <strong><code>layer</code></strong>, and <strong><code>sigma_level</code></strong> are deprecated.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="standard-name">3.3 Standard Name</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>standard_name</code></strong> attribute takes a string value comprised of a
standard name optionally followed by one or more blanks and a standard
name modifier.</p>
</li>
<li>
<p>The legal values for the standard name are contained in the standard
name table.</p>
</li>
<li>
<p>The legal values for the standard name modifier are contained in
Appendix C, Standard Name Modifiers.</p>
</li>
<li>
<p>If a variable has a <strong><code>standard_name</code></strong> of <strong><code>region</code></strong> or <strong><code>area_type</code></strong>, it must have value(s)
from the permitted list.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendataions:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>Use of the <strong><code>standard_name</code></strong> modifiers <strong><code>status_flag</code></strong> and <strong><code>number_of_observations</code></strong>
is deprecated, and the corresponding <strong><code>standard_names</code></strong> are recommended instead.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="flags">3.5 Flags</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>flag_values</code></strong> attribute must have the same type as the variable to
which it is attached.</p>
</li>
<li>
<p>If the <strong><code>flag_values</code></strong> attribute is present then the <strong><code>flag_meanings</code></strong>
attribute must be specified.</p>
</li>
<li>
<p>The type of the <strong><code>flag_meanings</code></strong> attribute is a string whose value is a
blank separated list of words or phrases, each consisting of characters
from the alphanumeric set and the following five: '_', '-', '.', '+',
'@'.</p>
</li>
<li>
<p>The number of <strong><code>flag_values</code></strong> attribute values must equal the number of
words or phrases appearing in the <strong><code>flag_meanings</code></strong> string.</p>
</li>
<li>
<p>The number of <strong><code>flag_masks</code></strong> attribute values must equal the number of
words or phrases appearing in the <strong><code>flag_meanings</code></strong> string.</p>
</li>
<li>
<p>Variables with a <strong><code>flag_masks</code></strong> attribute must have a type that is
compatible with bit field expression (char, byte, short and int), not
floating-point (float, real, double), and the <strong><code>flag_masks</code></strong> attribute must
have the same type.</p>
</li>
<li>
<p>The <strong><code>flag_masks</code></strong> attribute values must be non-zero.</p>
</li>
<li>
<p>The <strong><code>flag_values</code></strong> attribute values must be mutually exclusive among the
set of <strong><code>flag_values</code></strong> attribute values defined for that variable.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>When <strong><code>flag_masks</code></strong> and <strong><code>flag_values</code></strong> are both defined, the Boolean AND of
each entry in <strong><code>flag_values</code></strong> with its corresponding entry in <strong><code>flag_masks</code></strong>
should equal the <strong><code>flag_values</code></strong> entry, ie, the mask selects all the bits
required to express the value.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="coordinate-types">4 Coordinate Types</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>axis</code></strong> attribute may only be attached to a coordinate variable.</p>
</li>
<li>
<p>The only legal values of axis are <strong><code>X</code></strong>, <strong><code>Y</code></strong>, <strong><code>Z</code></strong>, and <strong><code>T</code></strong> (case insensitive).</p>
</li>
<li>
<p>The <strong><code>axis</code></strong> attribute must be consistent with the coordinate type deduced
from <strong><code>units</code></strong> and <strong><code>positive</code></strong>.</p>
</li>
<li>
<p>The <strong><code>axis</code></strong> attribute is not allowed for auxiliary coordinate variables.</p>
</li>
<li>
<p>A data variable must not have more than one coordinate variable with a
particular value of the <strong><code>axis</code></strong> attribute.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="vertical-height-or-depth-coordinate">4.3 Vertical (height or depth) Coordinate</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The only legal values for the <strong><code>positive</code></strong> attribute are <strong><code>up</code></strong> or <strong><code>down</code></strong> (case
insensitive).</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>positive</code></strong> attribute should be consistent with the sign convention implied by the
definition of the <strong><code>standard_name</code></strong>, if both are provided.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="dimensionless-vertical-coordinates">4.3.3 Parameterized Vertical Coordinate</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The <strong><code>formula_terms</code></strong> attribute is only allowed on a coordinate variable
which has a <strong><code>standard_name</code></strong> listed in Appendix C.</p>
</li>
<li>
<p>The type of the <strong><code>formula_terms</code></strong> attribute is a string whose value is
list of blank separated word pairs in the form <strong><code>term: var</code></strong>. The legal
values <strong><code>term</code></strong> are contained in Appendix C for each valid <strong><code>standard_name</code></strong>.
The values of <strong><code>var</code></strong> must be variables that exist in the file.</p>
</li>
<li>
<p>Where indicated by the appropriate definition in Appendix D, the <strong><code>standard_name</code></strong>
attributes of variables named by the <strong><code>formula_terms</code></strong> attribute must be consistent
with the <strong><code>standard_name</code></strong> of the coordinate variable it is attached to, according to
the appropriate definition in Appendix D.</p>
</li>
<li>
<p>The <strong><code>computed_standard_name</code></strong> attribute is only allowed on a coordinate variable
which has a <strong><code>formula_terms</code></strong> attribute.</p>
</li>
<li>
<p>The <strong><code>computed_standard_name</code></strong> attribute is a string whose value must be consistent
with the <strong><code>standard_name</code></strong> of the coordinate variable it is attached to, and in some cases
also with the <strong><code>standard_name</code></strong> attributes of variables named by the <strong><code>formula_terms</code></strong> attribute,
according to the appropriate definition in Appendix D.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="time-coordinate">4.4 Time Coordinate</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The time units of a time coordinate variable must contain a reference
time.</p>
</li>
<li>
<p>The reference time of a time coordinate variable must be a legal time
in the specified calendar.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The use of a reference time in the year 0 to indicate climatological
time is deprecated. This restriction only applies to the real-world
calendar as used by the udunits package.</p>
</li>
<li>
<p>Units of <strong><code>year</code></strong> and <strong><code>month</code></strong> and any equivalent units should be used with
caution.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="calendar">4.4.1 Calendar</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The attributes <strong><code>calendar</code></strong>, <strong><code>month_lengths</code></strong>, <strong><code>leap_year</code></strong>, and <strong><code>leap_month</code></strong> may
only be attached to time coordinate variables.</p>
</li>
<li>
<p>The standardized values of the calendar attribute are <strong><code>gregorian</code></strong>,
<strong><code>standard</code></strong>, <strong><code>proleptic_gregorian</code></strong>, <strong><code>noleap</code></strong>, <strong><code>365_day</code></strong>, <strong><code>all_leap</code></strong>, <strong><code>366_day</code></strong>,
<strong><code>360_day</code></strong>, <strong><code>julian</code></strong>, and <strong><code>none</code></strong> (case insensitive). If the <strong><code>calendar</code></strong> attribute
is given a non-standard value, then the attribute <strong><code>month_lengths</code></strong> is
required, along with <strong><code>leap_year</code></strong> and <strong><code>leap_month</code></strong> as appropriate.</p>
</li>
<li>
<p>The type of the <strong><code>month_lengths</code></strong> attribute must be an integer array of
size 12.</p>
</li>
<li>
<p>The values of the <strong><code>leap_month</code></strong> attribute must be in the range 1-12.</p>
</li>
<li>
<p>The values of the <strong><code>leap_year</code></strong> and <strong><code>leap_month</code></strong> attributes are integer
scalars.</p>
</li>
</ul>
</div>
<div class="paragraph">
<p><strong>Recommendations:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>The attribute <strong><code>leap_month</code></strong> should not appear unless the attribute
<strong><code>leap_year</code></strong> is present.</p>
</li>
<li>
<p>The time coordinate should not cross the date 1582-10-15 when the
default mixed Gregorian/Julian calendar is in use.</p>
</li>
</ul>
</div>
</div>
<div class="sect2">
<h3 id="coordinate-systems">5 Coordinate Systems</h3>
<div class="paragraph">
<p><strong>Requirements:</strong></p>
</div>
<div class="ulist">
<ul>
<li>
<p>All of a variable’s dimensions that are latitude, longitude, vertical,
or time dimensions must have corresponding coordinate variables.</p>
</li>
<li>
<p>A coordinate variable must have values that are strictly monotonic
(increasing or decreasing).</p>
</li>
<li>
<p>A coordinate variable must not have the <strong><code>_FillValue</code></strong> or <strong><code>missing_value</code></strong>
attributes.</p>
</li>
<li>
<p>The type of the <strong><code>coordinates</code></strong> attribute is a string whose value is a
blank separated list of variable names. All specified variable names
must exist in the file.</p>