Re: namespace prefix weirdness

So is this purely an aesthetic issue?  It has no effect on subsequent
processing?

The choice of namespace prefixes, unfortunately, is not completely
arbitrary, (a) because you might be using constructs that use namespace
prefixes in element or attribute content, and (b) because you might require
that the result document is valid against a DTD that disallows the presence
of certain xmlns:xxx attributes.

--- mods.xsl ---
<xsl:stylesheet version="2.0"
                xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
                xmlns:mods="http://www.loc.gov/mods/v3"
                xmlns="http://www.loc.gov/mods/v3">

<xsl:template match="mods:modsCollection" mode="enhanced-bib">
  <modsCollection>
    <xsl:apply-templates select="mods:mods"  mode="enhanced-bib"/>
  </modsCollection>
</xsl:template>

<xsl:template match="mods:mods" mode="enhanced-bib">
  <key>test</key>
  <xsl:copy-of select="."/>
</xsl:template>