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Definition of 'Body Part', another view

1995-04-19 04:36:45
Yet another message on this subject. I know the temptation is strong to hit
the 'Delete' key, but please don't. I am trying to bring a new view on
the subject..

I have been reading your last message again and again. Maybe this phrase
is the key:
This is absolutely wrong. The previous definition tied body part to multipart
structures only. This is not acceptable.
Which means that you (and perhaps some others) wanted to use the term
'body part' in the context of messages whose body is not of the multipart
type. Is that right ?

It can be done, of course, but I would have proceeded in the following manner:
1- invent a new term, say 'foobar', to replace 'body part';
2- replace 'body part', in the definition and wherever it appears in the
   document, by 'foobar'. Doing so ensures that none of the things that were
   correct (and there were many, since the document was the result of several
   years of work by many talented people) gets broken. It also frees the
   term 'body part', since it does not appear in the document anymore.
3- write a definition for 'body part', to let it be whatever you feel is
   necessary. I guess it would sit after the one for 'Body', since it
   would need to reference it. It would also need to reference 'entity',
   since a 'body part' can be found either in a 'message' or in a 'foobar',
   and step 2 would have made 'entity' the union of 'message' and 'foobar'.
4- then introduce 'body part' in the places of the document where you feel it
   is needed.
It may be that this last step will lead to the removal of all instances
of 'foobar'. My these is that it will not, because 'foobar' did play an
essential role at some places in the document.

Possible justification for that these:
According to the new definition, an entity can only have ONE body part.
Since the new body part includes the 'Content-' headers that are part of
the header of the entity (well, that's not in the definition I have seen,
but you stated it), and since those headers cannot meaningfully be
repeated in the header of the entity, it follows that an entity can only have
a single body part. It can of course have several foobars, which means that
foobar will be difficult to eliminate while speaking about entities
whose body is of the 'multipart' variety...

Some difficulties:
- if one looks at the foobars inside a multipart body, one will see that
they look like free body parts. Are they body parts ? No, for the reason
explained above, and also because...
- all the objects defined before the introduction of the new 'body part'
are 'physical': one can tell, in a 'top-level' message, at which character
each object starts and ends. Not so for the new body part: being the union
of a body and some headers that can be in the middle of some others, it is
rather a 'logical' object. This logical object appears in a 'pure'
form when it sits in a foobar, but not necessarily when it sits in a

So, I maintain that it was a mistake to try to fix a perceived problem
by redefining an existing object (body part). Indeed, a new object was
needed, and one can if so desired swap names to have the new object be
called 'body part'. To state it otherwise: no set of four definitions
suffices to say all the things that need to be said, a set of five is
necessary to work confortably. And the 'foobar' ? Call it 'multipart
element' or 'multipart component', or ???


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