The mark command allows you to prevent other CSops from doing a GETPASS or a SETPASS to a nickname. It can be used to indicate that you are dealing or dealt with a nickname. Note: Root users can override the mark command.
Example:
/msg nickserv mark WebMaster nick owner is a CSop
Sometimes users ask for passwords to nicks that they do not own, if such happens and it is fully investigated, marking the nick can prevent other CSops from wasting time investigating again. It also can be used to mark nicks of CSops, since they will not require other CSops to getpass their nicks for them. Mark, however, is a versatile command, and can be used to attach any necessary information to a nickname.