- nil - do not highlight the message at all
- 'keyword - highlight all instances of current nickname in message
- 'nick - highlight the nick of the user who typed your nickname
- 'nick-or-keyword - highlight the nick of the user who typed your nickname,
- or all instances of the current nickname if there was
- no sending user
- 'all - highlight the entire message where current nickname occurs
+ nil - do not highlight the message at all
+ `keyword' - highlight all instances of current nickname in message
+ `nick' - highlight the nick of the user who typed your nickname
+ `nick-or-keyword' - highlight the nick of the user who typed your nickname,
+ or all instances of the current nickname if there was
+ no sending user
+ `all' - highlight the entire message where current nickname occurs