EPUB: dbtimestamp PI in pubdate or date

[Thomas Schraitle <tom_schr@web.de>]

Hi,

currently, I'm investigating EPUB(3) and dates in pubdate.

It's not unusual to have the following <pubdate> inside an info, using the 
default date format:

  <pubdate><?dbtimestamp?></pubdate>

This works for HTML, FO, etc. except for EPUB. For EPUB, you get:

  WARNING: wrong metadata date format: '' in element bookinfo/pubdate. It must
  be in one of these forms: YYYY, YYYY-MM, or YYYY-MM-DD.

Well, I think the message is correct as there is really no text. It doesn't 
help to add a "format" pseudo attribute here:

  <pubdate><?dbtimestamp format="Y, m d?></pubdate>

This would lead to the same message.

Digging deeper into the EPUB3 stylesheets, I assume the "dbtimestamp" PI isn't 
supported at all. The pubdate is used as OPF metadata in the following 
template:

 <xsl:template match="date|pubdate" mode="opf.metadata">
   <xsl:variable name="date">
     <xsl:call-template name="format.meta.date">
       <xsl:with-param name="string" select="normalize-space(.)"/>
     </xsl:call-template>
   </xsl:variable>
  <!-- ... --->
 </xsl:template>

However, "format.meta.data" just checks if the given text is in the right 
format. If not, it displays the above warning message.

Now I'm wondering if this is the right approach. 8-) Shouldn't we distinguish 
between two cases:

1. date or pubdate contains only text
   We need to check, if the text is a valid date in the format needed by EPUB

2. date or pubdate contains no text, but <?dbtimestamp?>
   We ignore any format pseudo attribute and return a date in the format 
   "Y-m-d"

I would propose the following change:

 <xsl:template match="date|pubdate" mode="opf.metadata">
   <xsl:variable name="date">
     <xsl:choose>
      <xsl:when test="processing-instruction('dbtimestamp')">
        <xsl:call-template name="pi.dbtimestamp">
          <xsl:with-param name="format">Y-m-d</xsl:with-param>
        </xsl:call-template>
      </xsl:when>
      <xsl:otherwise>
        <xsl:call-template name="format.meta.date">
          <xsl:with-param name="string" select="normalize-space(.)"/>
        </xsl:call-template>
      </xsl:otherwise>
    </xsl:choose>
   </xsl:variable>
  <!-- ... --->
 </xsl:template>

Unfortunately, this won't work. The "pi.dbtimestamp" template doesn't allow a 
parameter "format". Looking into the template <xsl:variable> is used.

Could we change "pi.dbtimestamp" and use <xsl:param> instead of 
<xsl:variable>?  Or is there another solution that I can't see? 


What do you think?


-- 
Gruß/Regards
  Thomas Schraitle