A number in REXX is a character string that includes one or more decimal digits, with an optional decimal point. (See section Exponential Notation for an extension of this definition.) The decimal point may be embedded in the number, or may be a prefix or suffix. The group of digits (and optional decimal point) constructed this way can have leading or trailing blanks and an optional sign (+ or -) that must come before any digits or decimal point. The sign can also have leading or trailing blanks.
Note that a single period alone is not a valid number.