Differences of xercesImpl.jar, xercesImpl-J.jar, dom3-xercesImpl.jar ?

[Arnold Peters]

When I inspected my directories I found a lot of different xercesImpl.jar files
with different files and names. E.g.:

Are they all compatible?
How do I find out which version is a certain xercesImpl.jar.
Are the versions from different distributors/authors?
What are the differences ?

What about the accompanying jars like (dom3-)xml-apis.jar?

Arni