3 15 75  Constraints                 
  1. "Name" is an identifier of the variable. See the Help for the
"Parameter" table for more detailed information.
  2. "Expression" can be an algebraic formula, composed of integer
numbers, identifiers described above in this table, identifiers enumerated
in the "Parameters" table, parentheses '(',')', arithmetic operators
'+'.'-','/','*','**' and the sqrt( ) function. For raising to a power 
a^b the second operand must be an integer.
3. 'Comment' is a brief parameter description.