[mizar] Fixed variables

[Andrzej Trybulec <trybulec@math.uwb.edu.pl>]

In Freek's "Mizar's Soft Type System" we read:
 'Although in logic these are considered variables, in the Mizar 
community they are often looked as constants that are local to the 
proof. In the Isabelle community there are called fixed variables'

Wow, I was so sure that I had coined the name, that it is translation of 
Polish 'zmienne ustalone'. :-)

Anyway, it the Mizar community these are called fixed variables. I 
believe Jaskowski wrote (I have no access to "On the rule of supposition 
... " in the moment) that they may be interpreted as local constants.

Regards,
Andrzej