C, L, and R scattered throughout this play?

[Alcalay]

Hi. I literally just joined this forum cause I can't find an answer to this anywhere on Google. Which seems sort of silly at this point in history.
The question:
I'm reading Lady Windermere's Fan by Oscar Wilde. In the brackets, there always lie a few R's and L's and C's. Example: "[Exit Parker C.]" or "[Still seated at table L.]"
What the hell do they mean??

Please please help me, this is driving me insane.

[tailor STATELY]

Prolly Center, Left, Right: https://books.google.com/books?id=oT_rZizNcBAC&pg=PR10&lpg=PR10&dq="playwriting+terms"+abbreviations&source=bl&ots=jxFghWGx7R&sig=CZs_yIcV3zBHl2uK83GXMkajDzM&hl=en&sa=X&ved=0ahUKEwjw7NfB9_XLAhWCsYMKHW0vBJYQ6AEIJjAB#v=on epage&q=center&f=false

See page 5 acting area.

Ta ! (short for tarradiddle),
tailor STATELY