& setq()
 
  Syntax: setq(<number>,<string>)
 
  This function is used to copy strings into local registers. It 
  returns a null string; it is a purely "side effect" function. There 
  are ten local registers, numbered 0 through 9. They are cleared at 
  the start of each interactive command, but are preserved across the 
  command queue. They are most useful for storing complex function 
  evaluations which are used repeatedly within a single command. The 
  local registers may be read via the r() function, and a common use 
  of setq()/r() is to temporarily store the result of a complex 
  evaluation whose result is needed more than once.
 
  setq() can be used to improve the readability of MUX code, as well 
  as to cut down the amount of time needed to do complex evaluations.
 
  Example:
  >&TEST me=Test on [mudname()] at [time()].
  > say [setq(0,u(TEST))]'[r(0)]' has length [strlen(r(0))].
  You say "'Test on TestMUX at Tue Feb 23 17:00:51 1993.' has length 
  45."
 
  See Also: r(), setr()