> The XSL I wrote starts with this declaration under:
> <xsl:stylesheet version="1.0"
> xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
> xmlns:fo="http://www.w3.org/1999/XSL/Format">

That's your problem. You don't want the xmlns:fo namespace as you are
generating XHTMl not XSL-FO, so the only affect  of having that
namespace declaration is to add the same declaration to the output
(making it technically invalid XHTML). But what you do need is a
declaration for the http://ltsc.ieee.org/xsd/LOMv1p0 namespace as
without that you can not refer to any elements in that namespace.
add
xmlns:l="http://ltsc.ieee.org/xsd/LOMv1p0"
then you need to refer to LOM elements in the stylesheet as
l:lom etc match="lom" matches lom in no-namespace so does not match your
eleemnt match="l:lom" matches your element (even though it appears
without prefix in your soyurce file) You need to prefix -_all_
references to elements in the lom namespace (or any namespace) in xslt1.

(The FAQ will have more examples, as this is the most F of the AQs.)

David