4 wired DC Motor encoder?

Hi all,
I have a brushed DC motor and there is an encoder mounted to that.

Label of the encoder reads "INCREMENTAL ROTARY ENCODER, Sera Systems Eng., 16P, DC 5V-24V". And only 4 wires come out of the box.

-White/Blue
-Blue
-White/Brown
-Brown

I do not know which wire is what. Any comments?

Thank you!