For the following commands, CALC, IF, ELSEIF, SETVAR, and WHILE, the
Command Interpreter (CI) assumes that the argument supplied on the
command line is an expression. Additionally, you can force the CI to
evaluate an expression for any command by enclosing the expression in
square brackets and preceding the brackets with an exclamation point, e.g. ![].

Variables, functions and operators are combined to form CI expressions.
An expression can be as simple as a constant, e.g. 1, TRUE, or "abc",
or complex, such as

finfo (filename,"eof") mod (2^8)

The CI also does partial expression evaluation. For instance, in the
following example, the CI will not evaluate (B) if (A) is FALSE:

(A) AND (B)

Or, in this example, if (A) is TRUE, the CI does not evaluate (B):

(A) OR (B)

In other words, the CI reads an expression from left to right, and
performs the minimum evaluation necessary.

For additional information, enter VARIABLES, FUNCTIONS, and
OPERATORS at the HELP prompt.