PAR of constant envelope modulations (FSK,GMSK)

Hi to All,
I have 2 questions about PAR.

1) Is it right to say that the constant envelope modulations such as FSK or GMSK PAR value is equal to 0dB?

2) Crest factor for a sin wave is 3.01 dB.
http://en.wikipedia.org/wiki/Crest_factor

Why Crest factor for a FM modulated signal is 0dB.

http://www.ece.ucsb.edu/yuegroup/Tea...f_chapter1.pdf

the FM signal basically is a single sinusoidal carrier. Is not it?



Could you please clarify the difference in PAR values for a sine wave and FM signal?

Thanks in advance...!