9. Status Inquiry

‘Z’

Pops a value off the stack, calculates the number of digits it has (or number of characters, if it is a string) and pushes that number.

‘X’

Pops a value off the stack, calculates the number of fraction digits it has, and pushes that number. For a string, the value pushed is 0.

‘z’

Pushes the current stack depth: the number of objects on the stack before the execution of the ‘z’ command.