currently a <table> may have a <head>, but it does not support the idea of a trailer or footer, which is a fairly common facility in table modelling languages.
An example of when its needed comes from EEBO A04863, where the text at the bottom
self-identifies as being part of the table
<head>The Table of Battallions, reduced out of the grand square of men.</head>
<cell>289 289 256</cell>
<trailer>The end of the Table of Battallions reduced out of the battels of g. and squares of men: vpon the right side of euery leafe.</trailer>
The TCP folks have used <trailer> here, but we could use something else, or define a <foot>