How do attachments in message-mode work?

[Marcin Borkowski]

Hi all,

I know that attachments in message-mode are just inserted strings of the
form like

"<hash part type="image/jpeg" filename="..." disposition=attachment>
<hash /part>"

where "hash" is an actual hash character.

Where can I find the code responsible for parsing them?  I'd like to
know whether I could add another attribute (like "type", "filename", or
"disposition") and be sure it is going to be ignored.  (I want to hack
adding attachments so that the size is displayed along with other data.
I'd like also to change faces a bit, so that the values of the
attributes are more prominent, but I do not expect any troubles there.)

TIA,

--
Marcin Borkowski
http://mbork.pl