Tablespace DRSYS

Hello.
Time ago, when we installed 8.1.5, we made the mistake of creating a database with the wizard.
Now I'm cleaning, and I've found several tablespaces which I don't know what they are for.

Most of them are empty:
USERS
INDX
OEM_REPOSITORY
So I put them offline to see if somebody complains, and I will drop them soon.

I've seen that there is a DRSYS tablespace with some segments inside, all of them owned by a user called ctxsys.

Do you know what is this all about?
Do you think I can drop them safely?

Thanks

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Julio César Glez Suarez
Xixón, Asturies, Spain
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