Omnimark

Another world

An active community Omnimark's been around for years, and there are plenty of SGML developers with Omnimark experience.
A more mixed set of tools Omnimark is in many ways a more comprehensive set of tools than XSLT, with both an understanding of XML document structures and an appreciation of text processing.
Went free, then stopped Omnimark was available for free for most of last year, but reverted to payware this year. Keep those free CDs!