Some basic questions

[Dr. Ing. Carlos López]

Hello everybody:
I would like to know if there is a place where to find some basic information
about GMP. By "basic" I meant non-programmer info, but general one.
I am looking for:
.- How a number is represented in GMP
.- Is there something equivalent to the machine epsilon in GMP? If not, how
may I estimate a "tolerance" from the parameters which define the GMP environment?
.- Which is the largest representable floating point? An the underflow level?
Regards
Carlos