XMP & IPTC and their relationship.

[guilbault mailinglists gmail com]

Considering the work and thought you guys have been putting into managing 
metadata lately as well as Bengt Thuree's recent patch, I figured that you 
may want to check out the IPTC organization's specification for syncing with 
XMP metadata.  There's a fair bit of stuff that may (or may not) be useful to 
you guys.

http://www.iptc.org/IPTC4XMP/

For some time now, more serious photographers have stored their metadata in 
IPTC fields.  This system was created by photojournalists as a standard way 
of preserving copyrights and other important information (including 
keywords).  It has been standard for years now.  Lately, XMP has been pushed 
by Adobe as the way that metadata should be stored and it seems to be gaining 
traction.  It's main advantage is the more flexible XML structure it is 
designed around.  The above link addresses synchronizing these two metadata 
formats in a sensible way (mostly converting IPTC to XMP in a standard way 
actually).  It may also give you useful insight into XMP and IPTC and, 
hopefully, make things easier on anyone trying to work with either type of 
metadata. 

--Jonathan Guilbault.