Tk, and by extension, Perl/Tk has symbolic marking in Text widgets, i.e. tagging. The tags move logically as you do search and replace. You'd have to use the Tk search & replace instead of perl regex though. When you're done searching/replacing and tagging where it occured, you'd find the char position of each tag and then write the file for input to your super data munger. It's fairly straightforward, the SAMS Teach Yourself TCL/TK book (that I know of) explains how. Chris