syntax is slightly changed: -format is now -f format.
New option: -i name
This is a switch to control marked sections in SGML documents. Useful
for multi-lingual documents.
symbolic links for each cross reference label in the source file, thus
allowing external documents to link to a more or less fixed target,
rather that the numbered files which can change whenever the target
document is modified.
Bug fix: warn when a reference is made to a nonexistant label.
