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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>I have a TeX document for which I wish to be able to turn “on” or “off” selected portions of text in the typeset result, without painstakingly changing the .tex file each time. (Thus, for example, I do NOT wish to comment out certain lines, with %, only to undo, redo, etc. later.) Of course, I am willing to insert appropriate markers or delimiters in the .tex file once, and then somehow externally “flip a switch” to either print or not print the selected portion(s). Ideally, I’d even like to be able to turn on or off within {$ $} or within {$$ $$} . Is anyone aware of a method? Thanks. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My application is a class handout for which I wish to have both a complete version as well as an outline version to hand out to students, with key elements (e.g., proofs) omitted because they will be filled in during class (in an attempt to keep students fully engaged). Since the handout will constantly evolve, I don’t want to keep and constantly update parallel versions. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>