Question

What does the em mean in

<em:description>...</em:description>

This is an extract from a firefox addon install.rdf file. I am curious as to what the em part adds to this. I could not find a solution to this on Google either.

Answer 1

em is the XML namespace that contains the description element. At the top of the install.rdf file you should see an attribute like this:

xmlns:em="http://www.mozilla.org/2004/em-rdf#"

This tells an XML parser that the prefix em is bound to that URI. It’s what gives that particular description element meaning, and it’s how XML documents are able to have multiple description elements that don’t conflict (by tying each type of description to a different URI).