When formatting verbatim environments, this flag controls whether or not any attempt will be done to number lines. Enabling this flag doesn’t necessarily mean that the embellishments will succeed (that depends on other settings; see Section 2.11.2, “Syntax highlighter”).

If this flag is true, line numbering may be attempted. If it is not, the listings will always be presented without line numbers. This parameter has no effect if $verbatim-embellishments is “false”.