64. Typical rules also require refraining from actions that threaten the value of the online space or increase the risk that the system operator will face legal trouble in the real world. Many coherent on line communities also have rules preserving the special character of their online spaces, rules governing posted messages, discouraging "flaming" (sending an insulting message) or "spamming" (sending the same message to multiple newsgroups), and even rules mandating certain professional qualifications for participants.