[media-types] Re: Clarification about text/xml subtypes

Hello Orie, Andrea, others,

On 2026-03-22 06:29, Orie wrote:
> Hi Andrea,
> 
> Based on what I read, I would suggest to register application/opml+xml.
> 
> And note the deprecated aliases: text/x-opml
> 
> I’m not an XML expert, and possibly there are some critical details of
> text/ that I am not aware of that preclude the suggestion above.

No. There are some critical details of text/... that make it unsuitable 
in some cases, but application/... can always be used instead of 
text/.... See more below.

> Inline for the rest:
> 
> 
> On Thu, Mar 19, 2026 at 11:05 PM Andrea Pappacoda <[email protected]> wrote:
> 
>> Hi all!
>>
>> I'd like to ask what might be a dumb question about text/xml subtypes.
>>
>> I notice that there are almost no registered text/xml subtypes; all of
>> them seem to be subtypes of application/xml (like application/rdf+xml).
>>
>> I also notice that Section 4.1.1 of RFC 2046 says that text/* types MUST
>> use a CRLF sequence to represent line breaks.
>>
>> This leads me to think that text/xml subtypes must use CRLF for line
>> breaks, instead of simply LF. Is my understanding correct?
> 
> 
> I don’t know the answer to this, but I would guess sorta…

The requirement for CRLF (rather than simply LF) strictly speaking only 
applies to email (SMTP and friends). For HTML, LF should be fine.

> I don’t know what
> a text/xml subtype would be, since xml is the subtype in the example and
> +xml is a structured suffix for application subtypes that use xml.
> 
> 
>>
>> Also, is there a particular reason why there are no text/xml subtypes?
> 
> 
> Do you mean that there are no +xml based text/ subtypes?
> IIRC +xml comes from application/xml … so there are no text subtypes that
> use it… I think?

It's just too cumbersome to define and use text/...+xml types because 
that excludes some XML files in some circumstances (charsets, applications).

Regards,    Martin.

>> This all comes from a particular GitHub issue[1] about the possibility
>> of registering a media type for the OPML file format[2][3], which is
>> based on XML. The format currently uses either the text/x-opml media
>> type, application/xml or text/xml media types. There have been proposals
>> of registering text/opml+xml, or using the vendor or peronal trees, but
>> seeing the lack of any registered text/xml subtype got me wondering why.
>>
>> Note that I'm aware of the historical charset considerations for
>> text/xml vs application/xml, but they are not what I'm confused about.
> 
> 
> I’m not aware of these, so you probably know more than me, hopefully
> someone more knowledgeable will be able to answer your questions above.
> 
> 
>>
>> Please Cc me in replies as I'm not subscribed. Thanks! Bye :)
>>
>> [1]: https://github.com/scripting/opml.org/issues/20
>> [2]: https://en.wikipedia.org/wiki/OPML
>> [3]: https://opml.org/spec2.opml
>>
>> P.S. I had originally sent this mail to <[email protected]>, but
>> since discovered via 6838bis that the new mail address is @ietf.org. In
>> case this got delivered twice, I'm sorry.
>>
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> 
> 
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