Are the formats in DateTime::Format::Strptime extensible?

Dear List,

A while back, I needed to some routines to parse timestamps so I started 
using DateTime::Format::Strptime.  The times were uniformly formatted 
like "2012-03-13T07:43:07-07:00".  That /almost/ matched the pattern 
"%FT%T%z" but I couldn't figure out how to force the match.  So I ended 
up taking a shortcut and removing the final ":" before processing.

Now I want to recycle the code and handle a few more formats and I'd 
/really/ like it to be the case that I don't have to do any 
manipulations of the strings before parsing; I'd much rather just have 
the caller specify what the proper format is and go from there.

Any advice is appreciated,

dave