From the Glossary
E·ROS·TO·PI·A - n. - an imaginary place where beliefs and behaviors about sexuality, erotic desire, intercourse as well as gender roles, wiring and an individual's unique "twist" have evolved naturally without repressive dogma, shame-based stigma and control-based laws--a place free of the sexual dysfunction, jealousy, shaming and conflict in other societies. Welcome to the ancient, nomadic erostopia of Rivasor!
Note: Over countless generations, the men of Rivasor have evolved with cockswords of horsean proportions, and the women possess berries of preternaturally tight clench.
STAIN – verb: to ejaculate onto another's skin; noun: the visible mark roused by such contact.
When a Rivasoran man's semen makes contact with a woman's skin (on any part of her body), a unique mark--a stain--appears on her forehead within one to two hours.
Elders in the community can tell, therefore, who is mating with whom, for they can recognize, for example, the stain of the blacksmith's son (or the blacksmith, himself!) on the seamstress' daughter.
As for the royal stain, only a few people know what it looks like, and even fewer have actually seen it carried--for kings are forbidden from spewing their kreem as long as they hold the throne. Therefore, to carry the King's stain, as bed maiden Reina now does, is cause for much whispering and finger pointing among the Rivasor clusterfolk, as well as grave concern and calls for the King's abdication from within the royal court.