Active
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... unregistered, experimental, and for use only with the active
agreement of the parties exchanging them.
...
... file transfer, spreadsheets,
presentations, scheduling data, and languages for "active"
(computational) material. (The latter, in particular, can pose
security problems ...
... user agent would use this information to conduct a dialog
with the user, and might then send additional material based on that
dialog. More generally, there have been several "active" languages
developed in which programs in a suitably specialized language ...
... registrations MUST state whether or not they employ such
"active content", and if they do, they MUST state what steps have
been taken to protect users of the media type ...