Work flow name for approving the po

HI,
Can any body please give me a list of api and work flows for an purchase order(po) at different stages

at requisition level

api to create a requisition
api t0 cancel  a requisition
 api/work flow to approve a requisition

at rfq
api to create a rfq
api t0 cancel  a rfq
 api/work flow to approve rfq

at quatation
 
api to create a quatation
api t0 cancel  a quatation
 api/work flow to  approve quatation

at po
 
api to create a po
api t0 cancel  a po
 api/work flow to  approve po


and if we are working with interfaces tables should we need to use import standard purchase orders concurrent program