Response to Simon St.L. on Entities v. XLL

Rick Jelliffe ricko at
Mon Dec 1 06:02:01 GMT 1997

> From: Peter Murray-Rust <peter at>

> XML(SGML) entities (NOTATION) have traditionally used PUBLIC and FPIs
> (Formal Public Identifier) for adding type information. This works if there
> is a registry of FPIs for this purpose. Without it is not much use. 

(Peter Flynn had such a registry of FPIs this year.)

> My
> impression - and I'm happy to be corrected - is that there are few useful
> FPIs for Typing objects.
> As yet, MIME is not part of the XLL mechanism. I wish it was, and keep
> squeaking for it. If it isn't I suggest we use XDEV:MIME as a FUA
> 'frequently used attribute' in XML-LINKs.

You can make up your own FPIs *now* for all MIME types using the following 

<!NOTATION video-mpeg 
     PUBLIC "+//IDN 
     Multipurpose Internet Mail Extensions::video/mpeg//EN">

The important thing about an FPI is that it does not have to be syntactically
correct to work, unlike a system identifier.  OF course, getting an agreed
on form will be best.  

It is interesting to note that I found it very difficult to find the
official site for the RFC.  There is nothing I could find at IETF, IANA,
Internet Sosiety, and searching on websites did not help.  For people
in this situation, they can use FPIs with, for example:

<!NOTATION video-mpeg 
     PUBLIC "+//IETF RFC 2046::Multipurpose Internet Mail Extensions//NOTATION 

FPIs are a great idea because they do not have to correspond to
anything in a fixed location: they can be descriptive. 

Rick Jelliffe

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