IPTC Metadata for XMP (IPTC4XMP):

"IPTC metadata were employed by Adobe Systems Inc. to describe photos already in the early nineties. A subset of the IPTC "Information Interchange Model - IIM" was adopted as the well known "IPTC Headers" for Photoshop, JPEG and TIFF image files which currently describe millions of professional digital photos.

In 2001 Adobe launched a new metadata framework called "Extensible Metadata Platform - XMP" and made it available in Photoshop (version 7 and CS) and other CS products. Photoshop also implemented a simple synchronisation between the - now "legacy" - IPTC headers and metadata elements of the XMP framework which works back and forth.

In 2004 a joint effort of the IPTC, Adobe and IDEAlliance started to work on

* the "IPTC Core" Schema for XMP for a smooth and explicit transfer of metadata values from the IPTC Headers to the XMP framework * a specification on how to synchronise legacy IPTC header values with the new "IPTC Core" - back and forth."