Michael started with telling the background of IPTC. The IIM standard was introduced 1994. The current ITPC Core was published year 2005. Today those live in parallel. Proper synchronization of data in-between IIM and Core are very important. This must be handled by software.
There are several common misuses of IPTC-fields. One that used to be very common are that the date field is populated with scanning date instead date of the actual capture. Today several fields have different name in different applications, sometimes event with different software application versions. With localization this even get worse due to varying translations. It is important to have consequent naming.
Notes from the first Photo Metadata Conference. This conference was held in Florence, Italy june 7, 2007. It was organized by Cepic, IPTC and IFRA. These are my private notes published to give you some idea of what was discussed. I will later write some articles from the conference and publish those on BLF.se and DigitalFotografen.se, but probably only in Swedish. If there are any demand I might make a short translated version in English. You can find presentations and more information at phmdc.org and cepic.org .