registration process
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... RFC2045], are capable of carrying
arbitrary labeled content. A mechanism is needed to label such
content and a registration process is needed for these labels, to
ensure that the set of such values is developed in an orderly, well-
specified, and public manner.
...
...
In order to increase the efficiency and flexibility of the
registration process, different structures of subtype names may be
registered to accommodate the different natural requirements ...
... implemented. This was asserted in the past as a reason to limit the
number of possible media types, and it resulted in a registration
process with a significant hurdle and delay for those registering
media types.
...