The EOL_SPAN_REGEXP rule is similar to the EOL_SPAN rule except the match sequence is taken to be a regular expression. In addition to the attributes supported by the EOL_SPAN tag, the following attributes are supported:

HASH_CHAR and HASH_CHARS attributes are both optional, but you may only specify one, not both. If both are specified, HASH_CHARS is ignored and an error is shown. Whenever possible, use a literal prefix to specify a EOL_SPAN_REGEXP. If the starting prefix is always the same, use HASH_CHAR and provide as much prefix as possible. Only in rare cases would you omit both attributes, such as the case where there is no other reliable way to get the highlighting you need, for example, with comments in the Cobol programming language.

The regular expression match cannot span more than one line.

Regular expression syntax is described in Appendix E, Regular Expressions.

Here is an EOL_SPAN_REGEXP that highlights MS-DOS batch file comments, which start with REM, followed by any whitespace character, and extend until the end of the line: