What are WCDMA-IMT, PCS and CLR?

[2Fredsone]

Hi
I have some questions about cellular frequencies.
First, can somebody please tell me, what is WCDMA-IMT-2000, and is it the same thing as WCDMA 2100?
Also what does the PCS in WCDMA-PCS-1900 and the CLR in WCDMA-CLR-850 mean?

Regards...