Use Flags Attribute for Enum Type (UFAET)

Description:

C# allows you to use the FlagsAttribute to mark an enumeration as containing bit-mask flags. In this case, you should specify the FlagsAttribute.

Incorrect:

class PersistentObject {
    enum State {
        Dirty        = 0x10,
        Deteriorated = 0x20,
        Locked       = 0x40,
        Pinned       = 0x80
    };

    int state;

    void setDirty() {
        state |= (int)State.Dirty;
    }
}

Correct:

class PersistentObject {
    [Flags]
    enum State {
        Dirty        = 0x10,
        Deteriorated = 0x20,
        Locked       = 0x40,
        Pinned       = 0x80
    };

    int state;

    void setDirty() {
        state |= State.Dirty;
    }
}