User taggingThe idea isn't new and it has been posted as a feature request for various forum products and I believe, there are at least some mods for it (not for SMF though).Basically, what user tagging does is kinda simple. Using a special @Name,name1,name2: syntax, the mentioned member names will be converted into user profile links and, if the activity stream feature is enabled, the tagged (or "mentioned") member(s) will receive a notification that someone mentioned them in a message.Example:You write: @Velvet: look here... The member name will be converted into a profile link and the member will receive a notification (see attached image).The feature is totally optional. It can be disabled forum-wide with a single check box (in fact, like most of the new features, it is disabled by default and must be explicitly enabled).There is a permission that controls which member groups can use it, so if you wish, you could enable this only for a group of trusted members to prevent new members (possible spammers) from abusing this feature. If a member lacks the necessary permission, tags are simply not parsed at all.The maximum number of unique member IDs that can be tagged in a single message is limited to 10. That should be way, way enough for most situations.The notifications sent out to tagged members depend on the activity stream feature and like all other notifications, users can opt-out from seeing them.You cannot mention or tag yourself (well, obviously... doesn't make sense anyway )Member-name matching is case-insensitive, so @nightwish works even when the user name is actually Nightwish.Integrating this into the editor with a possible AJAX-powered lookup and auto-complete is considered, however, I'm a bit unsure about possible performance issues with such a feature. Member table lookups can be heavy, especially when looking for a name, not a member ID.Mis-spelled or non-existing names are filtered out. The message preview will show this, so it's possible to correct it before submitting a message.Tags are converted into profile links when a message is submitted, so when you later modify the message or another user quotes it, the tags are gone, so it isn't possible to get repeated notifications from the very same message.The characters that start and end a user tag are customizable. By default, a double @ will start a user tag, followed by a comma-separated list of one or more user names and finalized by a colon character. This format can be changed though and it is planned to add support to the message editor to allow easy insertion of the necessary code.A message can contain multiple tags with one or more members per tag, but overall, no more than 10 unique users can be tagged in a single message, unless you are the forum administrator or have permission to moderate the board.The notification will contain a link to the message that contains the tag and like for all other notifications, visiting this link will mark the notification as seen and remove it from the list of unseen notifications.