How to input data (a number) from operator?

Please, give me advice: which commands permit to ask operator to input a number to a variable?
(for example, the operator measures manually a size of smth and I want to get this size and to use it in running program).

For output there are (MSG,) and (PRINT,).

And how to input smth?

Have a look here forum.linuxcnc.org/38-general-linuxcnc-q...iable?start=10#57149
Should still work.

OK, Thanks, I'll try.

So strange that there is no simple especial command for this easy useful action.