xym­tex – Ob­so­lete: Type­set­ting chem­i­cal struc­tures

XyMTeX is a set of pack­ages for draw­ing a wide va­ri­ety of chem­i­cal struc­tural for­mu­las. The com­mands have a set of sys­tem­atic ar­gu­ments for spec­i­fy­ing sub­stituents and their po­si­tions, en­do­cyclic dou­ble bonds, and bond pat­terns; in some cases there are ad­di­tional ar­gu­ments for the het­ero-atoms on the ver­tices of het­e­ro­cy­cles. It is be­lieved that this sys­tem­atic de­sign al­lows XyMTeX to op­er­ate as a prac­ti­cal (de­vice-in­de­pen­dent) tool for use with LaTeX.
XyMTeX is re­ported not to be an easy en­vi­ron­ment to work in, be con­trast to the chem­fig pack­age (which sup­ports a sig­nif­i­cant pro­por­tion of XyMTeX func­tion­al­ity).
(Note: while XyMTeX was once up­loaded to CTAN, it ap­pears that the au­thor up­dates it reg­u­larly on the web; since its struc­ture seems to change reg­u­larly, the CTAN team no longer try to track it.)