[mizar] MML License

[Josef Urban <urban@ktilinux.ms.mff.cuni.cz>]

Hi,

I hate to open this problem, especially after arguing too many times that 
Mizar should be GPL-ed, but I need to add some license info to MPTP right 
now.

Is there a thing like "MML License" or "MML-derived work license"? 
The only relevant info I found is at
http://mizar.uwb.edu.pl/system/#distribution,
saying:

  The distribution of the Mizar system and the MML is free of charge for 
  non commercial purposes.

After that, there is some info on Mizar software (so probably not relevant 
for my purpose) and on PC Mizar System (Mizar User Declaration), which 
might be relevant (even for users of modified MML).

I definitely do not want to start any legalistic discussion, just need a 
couple of sentences to satisfy SUM and Mizar authors and make things clear 
for potential MPTP users.

Thanks for advice.
Josef