Yearless dates are valid HTML but flagged

[robinwhittleton]

HTML5.1 allows yearless dates, but epubcheck currently flags them. It looks like amending the current set of regexes in datatypes.rnc to include something like ([0-9]{2})-([0-9]{2}) would fix it but this is the first time I’ve looked at the code so I’ll defer unless this doesn’t get picked up.

(somewhat similar to #341)

[tofi86]

AFAIK EPUB 3 specifies a specific HTML 5 subset which is not HTML 5.1 (am I right @mattgarrish?) and the newer HTML versions are only supported by EPUB 3.1 which however isn't supported by EpubCheck yet.

[robinwhittleton]

Thanks for the reply. HTML5.0 also defines a yearless date format as valid for the datetime attribute, and it looks like EPUB 3.0 pretty much wholesale imports the W3C HTML5.0 spec (assuming XHTML serialisation)? Sorry if I’m getting this wrong, I’m new to EPUB stuff.

[mattgarrish]

Looks like a bug. From what I see, there's no accounting for yearless dates in the date.or.time datatype. I wouldn't modify html.date as that looks like it would allow in input/date which requires a year from my reading. Probably need a new date type like:

datatype.html5.date.or.time = datatype.html5.date | datatype.html5.month | datatype.html5.yearless | datatype.html5.time | datatype.html5.datetime.global

datatype.html5.yearless = xsd:token { pattern ='(--)?(0[1-9]|1[0-2])-(0[0-9]|[1-2][0-9]|3[0-1])' }

(All the other date patterns use simple [0-9] ranges, so maybe the above is a bit of overkill since it will still allow bad dates.)

[rdeltour]

Closed in #957