Re: problem with deciding whether to or not to print heading on last page : xsl-fo

count(preceding::number of invoice lines) will give the number of lines up to current line (not including the current line). So 1 must be added to get actual no. of lines.

i hope the following images gives you a better idea.

this is the logic used


This is the general kind of invoice received. No problem with heading in the last page


When there are only two lines in the last page, the logic still holds


But when there is only one line in the last page the conditional check 
if(total number of invoice lines==preceeding::number of invoice lines+1)  become true and the heading is not displayed.