See W3C documentation for the XHTML table model.
One cell in the table header, as opposed to an ordinary cell in a table
(#PCDATA | ext-link | related-article | inline-supplementary-material | break | mixed-citation | alternatives | inline-graphic | mml:math | bold | italic | monospace | overline | roman | sans-serif | sc | strike | underline | fn | target | xref | sub | sup)*
Any combination of:
... <floats-group> <table-wrap> ... <graphic copyright="inherit" id="tb3a" xlink:href="jpa_14_2_160_tb3a.tif" /> <table> <thead align="left"> <tr> <th colspan="1" rowspan="1"></th> <th colspan="5" align="center" rowspan="1">Variables</th> </tr> ... </thead> <tbody> <tr> <td colspan="1" rowspan="1">p<sub location="post" arrange="stack">1</sub></td> <td colspan="1" rowspan="1">a<sub location="post" arrange="stack">11</sub></td> <td colspan="1" rowspan="1">a<sub location="post" arrange="stack">12</sub></td> <td colspan="1" rowspan="1">...</td> <td colspan="1" rowspan="1">...</td> <td colspan="1" rowspan="1">a<sub location="post" arrange="stack">1n</sub></td> </tr> ... </tbody> </table> </table-wrap> </floats-group> ...
xhtml-table-1.mod