All X-PLOR statements are composed of words.

A one-character word.
A sequence of nonblank characters that contains no one-character words and that is enclosed by spaces or one-character words.
A quoted string, i.e., a sequence of any characters enclosed in double quotes (") (a double quote itself can be produced by """ ).
A one-character word comprises special letters:
    )     $\vert$     (     $\vert$     :     $\vert$     @      $\vert$     =
In the case of mathematical expressions (such as vector statement and evaluate statement), one-character words constitute a larger set of special letters:
    )     $\vert$     (     $\vert$     :     $\vert$     @      $\vert$     =     $\vert$     $<$     $\vert$     $>$     $\vert$      #     $\vert$     $*$     $\vert$     ^     $\vert$     ~     $\vert$     +     $\vert$     -     $\vert$      $/$

Characters between comment braces { } or after an “!" on the same line are always ignored. The carriage return is treated as a space. Unless the word is a quoted string, all letters are converted to uppercase upon parsing.

Xplor-NIH 2023-11-10