The wizards of PernMUSH generally believe that what goes on in private rooms (rooms which are owned by individual players, not builder characters, and designed as private locales such as a bedroom or a weyr (rider's bedroom)) between consenting players is the players' own business.
However, in public areas of the MUSH, including public rooms and the knot chat channels, the wizards expect that players will follow a social code much like that in real life, where conversations and roleplaying are kept from becoming overly explicit, designed for a "PG" audience (one which includes children under 12). PernMUSH is a relatively anonymous environment, and so the wizards cannot take responsibility for minors who may witness or participate in sexually graphic roleplay.
PernMUSH is designed as a roleplaying environment which may include some aspects of people as sexual beings, but it is not a pornographically themed MUSH, and players should keep this in mind in their public roleplaying. Characters who do not follow these guidelines will be asked to stop, and may be +booted by a wizard. Mating flights are not exceptions to this policy, and roleplay in public areas like Living Caverns and Bowls should reflect this.
In line with this philosophy, leaders of areas, or people in charge of training (Apprentice Masters, Weyrlingmasters, etc.) are prohibited from requiring players to participate in roleplaying situations, or explicit discussions, based on sexual acts, in order to complete training or to gain a new rank. Any leader who does so may be removed from his/her position, at the discretion of the wizards.
The atmosphere of an IC area should never intimidate players not interested in roleplaying romance/sex. As in real life, Pernese are not required to flirt in public.
In the specific case of Weyr life, riders should be aware that the greater acceptance of various modes of sexuality that is present in the Weyr canonically does not mean that Weyrs are exempt from these guidelines. No rider is required to participate in mating flights. Players involved in mating flights should be left the option of having their dragon lose the flight. Riders whose dragons win mating flights are not required to roleplay sexual intercourse, although it can be assumed, canonically, to have occurred for background purposes. At the same time, riders should be aware that canonically, their dragons will have urges to rise to mate - players can choose to not actively roleplay this aspect of life, but specifically roleplaying a dragon with a lack of a reproductive drive should be cleared with the Weyrleaders first.
Rape tinyplots must be cleared with the IC area leaders first. Generally, these plots are discouraged, as this is an extremely sensitive issue and not really suited to the PernMUSH roleplaying environment. As character background, abuse and rape should be handled with caution - both for the reasons stated above and because it's not canonical to go around proclaiming that these things have occured.