| It's a function of the UA
You can't send a BP15 across an 84 connection but there are a number
of other bodyparts defined which you can, including BP14.
If the message contains anything not defined in the 84 standard then
the message needs to be downgraded, but apart from that, the MTA
shouldn't really care.
mike
|
| .1 is not entirely accurate.
To start off with, the 84 standard (X420) only declares BP0-BP11,
(and a number of these weren't actually defined). However, widely
accepted agreements have extended this in two differant directions.
1) The X.400 Stable Implimentation Agreements state (7.5.3.6.2)
"All Bodyparts with identifiers in the range 0 up to and including
16K-1 are legal and should be relayed." So you CAN send a BP15
across an 84 connection if the MTA conforms to this agreement.
Whether the receiving UA will understand it is a seperate matter.
2) The Stable Implimentation Agreements extended the Red Book
definitions to include Nationally Defined bodyparts (ie BP NN
where NN=X.121 Country code - for example 310=USA 234=UK) and
also declared "Recommended Practices" for "Binary Data Transfer"
(aka BP14) and "Office Document Architecture Transfer" (aka BP12)
[sections 7.12.7 and 7.12.8]
re: .0
X.400 doesn't define an "attachment"; the content of a IPmessage can
contain a sequence of bodyparts (see above). If you want to have the
highest degree of interoperability across multiple vendors, you stick
with the lowest common denominator - ie IA5. If you want the highest
degree of functionality you use a richer set (including privately
defined bodyparts and/or extensions), but of course this can impact
interoperability. (Witness the number of vendors we have tripped up
through our usage of P1 extensions and ForwardIPMessage by ALL-IN-1
and XMR, or our usage of USA310 for encapsulation by MRX and MB400,
or conversely Microsoft [and others] through use of a particular type
of BP15 known as the "file transfer bodypart" [IMHO a real hack]).
Putting 'stuff' in a BP14 doesn't give the receiving agent even the
slightest clue as to what the octets represent. So if you know that
your "attachment" is text, and it can be represented using one of the
'standard' text bodyparts (character set and formatting issues come
into play here) then you enhance your interoperability by using them.
Dave
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