>>--/-----.-----DIRECTIVE-NAME=parameter(s)-.--->< +-----DIRECTIVE-NAME--------------+
The syntax of the Compiler directives is shown using diagrams called "railroad tracks", in which a directive and its parameters are shown joined by lines indicating the order in which they should be written. You read these diagrams from left to right. Each diagram starts with $$ and ends with $%. Sometimes the track forks to show alternatives and then joins up again. The length of a track has no significance.
If a parameter is specified after a comma, but the filename is omitted, the directive must be preceded by a slash (/). Otherwise, the directive is incorrectly assumed to be a filename.
Comments:
Contains any additional information about the directive.