Rating

I use the same rating as is used for movies shown in US-cinemas.
In detail that is

G

General audiences. All ages admitted.

PG-8

Parental guidance suggested. Some material may not be suitable for children younger than 8

PG-13

Parental guidance suggested. Some material may not be suitable for children younger than 13

R

Restricted. Under 17 requires accompanying parent or adult guardian.

NC-17

No one under 17 admitted


this means in general:

G is a story that has no controversial ideas, language, or even hints at any type of sexual interaction.

PG-8 could perhaps have a tiny bit of mild adult language on maybe slightly controversial topics and violence (I would consider GR (US-version) to be rated PG-8)

PG-13 has some adult language, definite hints at violence or sexual tensions (perhaps we even see people going off together into a bedroom and we know what they are going to do, but it's not described – that sort of thing).

R and NC-17 are where you get into the more graphic descriptions of violence and / or sex. Also there can be a lot of adult language.

Adult language in this content means: swear words, impolities, wordplays dealing with violence, sex, and more.

Fanfic

Bureau of Extra-Terrestrial Affairs