Related to PO Versions

While working on PO versions

I found entries in EREV, CDHDR, CDPOS.....

But when i Check in se 37 for FM "BBP_PD_PO_GETDETAIL" and 'BBP_PD_CTR_GETDETAIL'

or cheked for table 'E_VERSION ' or Transaction BBP_PD

I didnt found anything.... Not a function module or table or transaaction so please let me know how i can aceess PO version Data....