1.10. Structure and General Syntax

A Rexx program is built from a series of clauses that are composed of:

Zero or more whitespace characters (blank or horizontal tabs) (which are ignored)
A sequence of tokens (see Section 1.10.4, “Tokens”)
Zero or more whitespace characters (again ignored)
A semicolon (;) delimiter that the line end, certain keywords, or the colon (:) implies.

Conceptually, each clause is scanned from left to right before processing, and the tokens composing it are identified. Instruction keywords are recognized at this stage, comments are removed, and sequences of whitespace characters (except within literal strings) are converted to single blanks. Whitespace characters adjacent to operator characters and special characters are also removed.