$begin tag$$. . . end  See Also getting started Purpose OMhelp ignores all input in a file except between a begin command and a matching end command. The cross reference tag for the corresponding section is specified by tag . Leading and trailing white space is ignored and there can be no  characters in tag . Example The following input file contains two sections. The first is named "First Subject" and is cross referenced as "one". The second is named "Second Subject" and is cross referenced as "two". In addition, each of the sections has a cross references to the other.  /* begin one$$$section First Subject$$This section is similar to cref/the second section/two/$$.      ...      $end */ Other text /*$begin two$$section Second Subject$$      This section is similar to      $cref/the first section/one/$$. ...$end      */      Other text 
No two sections can have the same cross reference tag . (Note that upper and lower case letters are considered equal when comparing cross reference tags).  Cross reference tags that begin with the underbar character _, and the dot character ., are reserved by OMhelp and cannot be used in begin commands.