Why the "Embedding" attribute set? Why not just use "object"?

I can't work out what it is that including the "Embedding" attributes
in the common attribute set offers that the "object" tag can't already
do in a neater and more general way - I'd appreciate a pointer to the
discussion that led to this decision.

I tried to check the comment archive to see if this question was
already answered, but the large amount of archived spam made this
impossible...
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\/ o\ Paul Crowley
/\__/ www.ciphergoth.org