I am trying to create a vCard XML and using the UID to identify our users but am unsure about the "IANA Registered Identifir Format" and where I can find more information about these identifier's. Below is an extert from: http://www.zvon.org/tmRFC/RFC2426/Output/chapter3.html.
The type can include the type parameter "TYPE" to specify the format of the identifier. The TYPE parameter value should be an IANA registered identifier format. The value can also be a non-standard format.
Type example:
UID:19950401-080045-40000F192713-0052
Any information regarding the IANA identifiers would be helpful as we have already contacted IANA and they have no knowledge of these.