use DC for Metadata in OMDoc.
There seem to be some of the %-codes for metadata, they should become OMDoc metadata:
%K A140000 nonn,easy
%A A140000 _T. D. Noe_, May 02 2008
should become
<omdoc id="...">
<metadata>
<dc:source>http://OEIS.org/A140000</dc:source>
<dc:creator>T. D. Noe</dc:creator>
<dc:date>May 02 2008</dc:date>
<dc:subject>nonn</dc:subject>
<dc:subjecct>easy</dc:subject>
</metadata>
... the rest ...
</omdoc>
The date should probably be in http://www.w3.org/TR/NOTE-datetime form (there is a parsing problem here).