Fresh, crispy learn buffers with a sane size for your gtranslator auto translation pleasures!
Erhm, wait, what is a learn buffer? -- Ok, this is a case for our FAQ where this and some further questions are answered for your pleasure!
If you're searching the official spec of UMTF (currently in version 1.0) you can grab this small tarball here and look inside it for a DTD, example file and the definition README.UMTF which is quite explanatory; the most recent version of the specification is found in GNOME CVS under gtranslator/doc/UMTF/ or per CVS webview.