The POP reference article from the English Wikipedia on 24-Jul-2004
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POP

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POP and PoP can be:

1. Post Office Protocol, a protocol used to receive e-mail from a mail server.

2. Point of Presence, the point of physical connection between telecommunications networks.

3. PowerPC Open Platform, a computer hardware reference design released by IBM for free use in 1999. The successor of CHRP.

4. Probability of precipitation, used in a weather forecast to define the chance that rain, snow, or other precipitation will fall during the specified period.

See pop for other, non-abbreviated meanings.