this`is`a`package`of`commutative`diagram`macros`built`on`top`of`xy\-`pic`by`michael`barr`\(email:`barr@barrs\.`org\)\.`its`use`is`unrestricted\.`it`may`be`freely`distributed,`unchanged,`for`noncommercial`or`commercial`use\.`if`changed,`it`must`be`renamed\.`inclusion`in`a`commercial`software`package`is`also`permitted,`but`i`would`appreciate`receiving`a`free`copy`for`my`personal`examination`and`use\.`there`are`no`guarantees`that`this`package`is`good`for`anything\.`i`have`tested`it`with`latex`2e,`latex`2\.09`and`plain`tex\.`although`i`know`of`no`reason`it`will`not`work`with`amstex,`i`have`not`tested`it\.