About Tripcodes...

The FAQ here is a little vague on some points:
FAQ says short word.  Must it be a word or can it be a random string?
Max length?
Case sensitive?
Forbidden characters? (I assume # is one)
Link to more in depth info?

Thanks in advance
les

ok so i have an semi old emachines and it wont turn on the light goes on and no fans start up i tested the power supply now what?