Comparing text strings

Hello,

I am trying to compare two strings, page_start.txt and page_end.txt in order to build an LEP using page ranges and want to output the single page thus avoiding "P1 to P1....."

However, I am struggling getting <specval attname="page_start.txt" attloc="#FOSI" attval="#EQ#page_end.txt"> to work.

Is the syntax correct here, or if it is, are there any alternative methods for comparing strings within a FOSI ?

Thanks

Andy