Different Standard Order Type

Dear All,

I am currently using GBI in Enterprise Resource Planning course.

We are at Sales and Distribution Module. In the Exercise we are creating a sales order using OR type. But, when I check by F4 I found out that there are many code for Standard Order:

CMDM Standard Order
CMR Standard Order
CMRC Standard Order
CMRP Standard Order
DMRB Standard Order
DMRP Standard Order
DMRR Standard Order

Please tell me where I can get more information about the above standard order types.

Thank you

MW