define doc metadata properties

[xquery]

We could provide a list of document metadata properties that every xproc processor must support. Maybe useful to have a normative section (very small) eg.

• name/uri
• content-type

and non normative list.

[vojtechtoman]

Just thinking out loud: some info about the origin/history of the document? Like the name of a step that produced the document or maybe even an accumulated list of steps that the document passed through; timestamps; ...

[ndw]

See also: issue #146

[ndw]

See also: issue #138