I'm going to use some title tags to show what exactly hides under mature and adult content, what type of artwork it is and if you can safely watch it.

The list, it's more a reminder for me that a list for you, sorry for any possible bothering!
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[G] - general, safe artwork without any mature things such as blood.
[N] - nude, artistic nudity.
[F] - strong language, some blood, mild violance.
[B] - fetish content.
* [BS] stands for sexual fetishes (ex.: frotting, penetration) and [BN] for nudity without further sexual process (ex.: shibari, petplay).
[S] - sexual content.
[E] - severe violence, gore, lots of blood.
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I work with different things and want to clarify it all ;w;
Someone may feel sick of blood but okay with nudity, so some additional marks won't hurt. You may forget about them at all, no need to remember all these.