If I put up plain text, I want the plain text to follow some regularization rules, and ZML is the only game in town actively working with etexts (as far as I know at least -- I do recall two other text regularization schemas, but don't know if the authors are doing anything with them.)
There are several schemes in active use, including: wiki markup: http://en.wikipedia.org/wiki/Wiki_markup STX: http://www.zope.org/Members/jim/StructuredTextWiki/FrontPage (Structured Text) by Jim Fulton, e.g. for Zope and ZWiki reStructuredText: http://docutils.sourceforge.net/rst.html for Python's DocUtils Markdown: http://daringfireball.net/projects/markdown/ by John Gruber of Daring Fireball (I'm not sure if any are being used for the same type of etexts as PG, but it seems likely that the overall level and diversity of activity and tools are more important. e.g. I think all of the above include source code, typically using a friendly "attribution" license.) My own approach (from 1995) plus links to several others is here: No-Tags Markup: http://prefab.com/ssl/notagsmarkup.html -- Cheers, Scott S. Lawton http://Classicosm.com/ - classic books