gEDA-user: mosfet design help

[gene glick]

I want to build a mosfet inverter that also translates voltages. Pretty 
much standard mosfet inverter, nmos is lower transistor, pmos is upper 
transistor.  The upper pmosfet Vsource is +5VDC, and mosfet Vsource is 
-5VDC.  But, the gate voltage is +/- 50VDC.

Although the gate voltage exceeds the turn-on threshold of the mosfet's 
- but does it violate any max values for Vgs or Vgd?  At these levels, 
the Vgs is going to around 55 volts.  The Vds is fine, and is easy to 
select a transistor for these levels.

It's not clear to me what the Vgs and Vgd maximums are, from reading 
various mosfet data sheets. Any help?

gene