classifiers and packaging types

[Ch...@emc.com]

I'd like to have a better understanding of classifiers and package types.

The packaging type is supposed to indicate the package type of the artifact.  Simple enough.  But does this carry through to any extra artifacts that I might attach to the pom?  Or is this purely for the "primary" artifact.

And, then, when attaching other artifacts to the pom, is packaging even useful?  Or should I use classifier for this task?