[Standards] Clarification for XEP-0054: private fields

Wichert Akkerman wichert at wiggy.net
Thu Sep 19 07:01:29 UTC 2019

Hi everyone,

I am looking for a clarification on XEP-0054. The history description for the XEP mentions that it essentially encapsulates draft-dawson-vcard-xml-dtd-01 over XMPP, with changes to using xuppercase for elements and adding JABBERID and DESC. draft-dawson-vcard-xml-dtd-01 also documents private fields [1], with a basic example:

        PRODID="-//HandGen//NONSGML vGen v1.0//EN">
   <fn>Frank Dawson</fn>
   <n>  <family>Dawson</family>
   <tel tel.type="WORK MSG">+1-617-693-8728</tel>

Unfortunately it forgot to include this in the DTD. This was extended later in draft 2 [2], and fully defined in the DTD for RFC 2426.

My question is: are implementation of XEP-0054 supposed to a) strictly use the DTD from XEP-0054, and thus required throw away any extra elements not mentioned there, b) support private fields since they are mentioned in draft-dawson-vcard-xml-dtd-01, or c) be liberal and preserve unknown elements?

This appears to be a fairly common question for ejabberd, which allowed unknown fields up to 16.11, after which it started throwing them away.


1: https://tools.ietf.org/html/draft-dawson-vcard-xml-dtd-01#section-4.2 <https://tools.ietf.org/html/draft-dawson-vcard-xml-dtd-01#section-4.2>
2: https://tools.ietf.org/html/draft-dawson-vcard-xml-dtd-02#section-4 <https://tools.ietf.org/html/rfc2426#section-3.8>
3: https://tools.ietf.org/html/rfc2426#section-4 <https://tools.ietf.org/html/rfc2426#section-4>
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