#670 Attribute definitions are slightly inconsistent

[Martin Holmes]

Sarah Milligan points out that these attribute definitions don't quite align:

when-custom supplies the value of a date or time in some standard form.

notBefore-custom specifies the earliest possible date for the event in some custom standard form.

notAfter-custom specifies the latest possible date for the event in some custom standard form.

from-custom indicates the starting point of the period in some standard form.

to-custom indicates the ending point of the period in some standard form.

Should the word "custom" always appear, or should it not appear? It's more important that they be consistent since they're now listed together in the ND chapter.

[James Cummings]

I would say that it should always appear in those definitions. I've assigned to myself to implement should no one complain in a reasonable length of time.

[Stefanie Gehrke]

Implemented this at revision 13065.

[Martin Holmes]

Update @versionDate on changed elements in the last commit. This can be closed-fixed now.