Traditionally Windows used a special character '1a'x (end-of-file) to signify the end of a text file. Although today use of this special end-of-file character has become less common, some editors may still append it to the end of a text file. Unix-like systems do not use a special end-of-file character in text files.

Rexx will honor the end-of-file character '1a'x within a Rexx program source file on both Windows and Unix-like platforms. It will not scan the source file beyond any end-of-file character it finds. This means, that a character '1a'x cannot be directly used within a Rexx program source file, for example within a literal string or a comment.