Arithmetic expressions
Arithmetic expressions are used as operands of certain conditional and arithmetic statements.
An arithmetic expression can consist of any of the following:
1. An identifier described as a numeric elementary item (including numeric functions)
2. A numeric literal
3. The figurative constant ZERO
4. Identifiers and literals, as defined in items 1, 2, and 3, separated by arithmetic operators
5. Two arithmetic expressions, as defined in items 1, 2, 3, or 4, separated by an arithmetic operator
6. An arithmetic expression, as defined in items 1, 2, 3, 4, or 5, enclosed in parenthesis
Any arithmetic expression can be preceded by a unary operator.
Identifiers and literals that appear in arithmetic expressions must represent either numeric elementary items or numeric literals on which arithmetic can be performed.