Clarify that the time format shouldn't include leap seconds

Author: jdesrosiers

specs/jsonschema-validation.md

@@ -402,14 +402,23 @@ Date and time format names are derived from
 format is from ISO 8601 as formalized into ABNF by RFC 3339 Appendix A.
 
 - *date-time*: A string instance is valid against this attribute if it is a
-  valid representation of the "date-time-ext" rule in RFC 9557
+  valid representation of the "date-time-ext" rule in RFC 9557. This SHOULD
+  allow and validate published leap seconds. See RFC 3339, section 5.7.
 - *date*: A string instance is valid against this attribute if it is a valid
   representation according to the "full-date" ABNF rule in RFC 3339
 - *time*: A string instance is valid against this attribute if it is a valid
-  representation according to the "full-time" ABNF rule in RFC 3339
+  representation according to the "full-time" ABNF rule in RFC 3339. This MUST
+  NOT include leap seconds.[^3]
 - *duration*: A string instance is valid against this attribute if it is a valid
   representation according to the "duration" ABNF rule in RFC 3339 Appendix A
 
+[^3]: The `time` format represents a time value that is independent of any
+specific date, such as a scheduled time of day or a measured duration. Because
+there is no date, it is not well suited for capturing a moment in time. For
+that, you would need `date-time`. Because `time` isn't for capturing a moment in
+time, leap seconds don't make sense because leap seconds only apply to
+specific dates. See RFC 3339, section 5.7.
+
 Implementations MAY support additional attributes using the other format names
 defined anywhere in that RFC. Implementations SHOULD NOT define extension
 attributes with any name matching an RFC 3339, RFC 9557, or ISO 8601 format