Well, if you`re using display:table you certainly will face some day a situation where you need to verify/test some attribute in the current register to show or not something(maybe a different situation but you need to verify something).
The fact is, display:table will set an attribute in the PageContext, this attribute name will be based on uid or id(the main difference between uid and id is backward compatibility).
With that(say) you`ve set the id attribute of display:table to row. Verifying an attribute in the current row is as easy as using the #attr.row.
For example:
<display:table id="row" ... <s:if test="#attr.row.you_attribute == 12"> [....]
That`s it, best luck.