>But it is not so easy to prevent some program trick.
>Sure, you have to exclude EVAL/COMPILE/EXECSCRIPT/Macro,
>otherwise the job of user containment becomes almost impossible
>
>

>#define INT myInt
>
>CLEAR
>
>? INT(3.5)
>
>variable=0h494E5428332E3529
>
>* multiform
>? EVALUATE(m.variable)
>? EVALUAT(m.variable)
>? EVALUA(m.variable)
>? EVALU(m.variable)
>? EVAL(m.variable)
>
>? EXECSCRI("return "+m.variable)
>
>variable = ''+variable
>? &variable
>
>PROCEDURE myInt(x)
>  RETURN "don't try to execute INT()"
>

I had already thought of that. The place where I want to contain user imagination is one where I let him write only one expression (not a complete program).
So I have to check for the existence of the EXECSCRIPT function.