These file extensions don't seem to have anything at all to do with
Java.  Where did you "come across" this, and what is it?  That might
provide some clues as to the questions you're asking.  Perhaps the
deployment product you found defines and uses those file extensions?

There aren't very many file extensions that are java related.  Unless
I've missed something, a fairly complete list would be .java, .class,
.jar, .war, .ear, .jsp, .jnlp, .jad, and questionably .properties
(although nothing but a very loose convention really defines the latter
as an extension).  You might include .mf, but it's really part of a
complete filename (/META-INF/Manifest.mf), and there are no general-
purpose uses of that extension, so I don't consider it a specific
extension.  There are also a number of other extensions that are even
more loosely associated with stuff... a lot of struts actions are mapped
to ".do", for example, and JSF page references sometimes but not
necessarily use .jsf.  But these aren't even to the point where I'd call
them widely recognized.