presence service
Click on the red underlined text to get to the source
...
[IMP-REQS] also stipulates that presence services must be separable
from instant messaging services; i.e., it must be possible to use the
...
... from instant messaging services; i.e., it must be possible to use the
protocol to provide a presence service, an instant messaging service,
or both. Although the text of this memo assumes that implementations
...
... deployments will want to offer a unified instant messaging and
presence service, there is no requirement that a service must offer
...
... requirement that a service must offer
both a presence service and an instant messaging service, and the
protocol makes it possible to offer separate and distinct services ...
... instant messaging, and is not required to support both if only a
presence service or an instant messaging service is desired.
...