What do strophe a and antistrophe a refer to?

Stophe and
antistrophe are terms denoting the movement and counter movement of
the chorus from one side of their playing area to another.  Choral odes and dances serve
to separate one scene from another since there was no curtain in the ancient Greet
theater.  They also comment on the action, reinforce the emotion, and interpret the
situation.

Strope is a turn and antistrophe is the turn the
other way.  Along with the epode, or added song, these were all
sung while the chorus danced.  Sometimes the chorus performs dance movement during
certain portion of the scenes themselves.  In Sophocles's play, Oedipus
Rex, for instance, there are strophe 1,
antistrophe 1, strope 2,
antistrope 2, and strophe 3,
antistrophe 3.  Perhaps in other additions they be
labeled strope a, b, and c as well as
 antistrophe a, b, and c.