Updates to "Writing ScrollKeeper OMF Files"

[Dan Mueth <muet alumni uchicago edu>]

I just uploaded a new version of "Writing ScrollKeeper OMF Files" to:

http://scrollkeeper.sourceforge.net/documentation/writing_scrollkeeper_omf_files/index.html

The changes are minor, but there are three things which I want to point 
out:

1) Explicitly state the encoding on the top line of the OMF file.  It
isn't necessary for UTF-8 or ASCII docs, but it is a good habit to start.  

eg: <?xml version="1.0" encoding="UTF-8"?>

2) Include a DOCTYPE declaration as shown in the example.  Thanks to
libxml2's support of XML catalogs, the local version of the DTD can be
found without going onto the net.  I did upload a copy to its new official
location on the net though, in case somebody blows away their XML catalog.

eg: <!DOCTYPE omf PUBLIC "-//OMF//DTD Scrollkeeper OMF Variant V1.0//EN" 
"http://scrollkeeper.sourceforge.net/dtds/scrollkeeper-omf-1.0/scrollkeeper-omf.dtd";>

Note that ScrollKeeper currently keeps track of the location of the DTD on
the system explicitly, so things will still work if this declaration is 
missing. However, an XML file is not technically valid if it doesn't
explicitly specify its DTD.  In the future, we are likely to maintain 
compatibility with multiple DTD versions and convert OMF files between 
them with stylesheets, so it will be convenient to know which DTD version 
each OMF file was written to.

3) To validate an OMF file which declares its DTD:
	xmllint --noout --valid foo-C.omf
The correct version of the DTD will be found locally, if ScrollKeeper is 
installed, or else on the net if SK isn't installed.

Dan