Manipulating/adding fields to exif-data iptc

Question

when looking into metadata of images I was wondering how standardized this data actually has to be. Is it possible to add a custom field for an application? I understand that it might be not readable by common applications but what way would you suggest to add some custom meta-data as in "Custom value: 1000" ? thx for your suggestions, links, info, etc?

Answer 1

XMP supports custom namespaces and fields - but I don't think EXIF or IPTC do.

See http://www.adobe.com/devnet/xmp.html for further documentation