Hello,
In SPRO go to Additional Information --Display key--IMG Activity.
Then open the Material Requirements Planning menu path so in Additional Information last four digits are the direct transaction codes like
OMI2, OMI3, CO09, OMD0, OPPR, OX09, OMI8, OPPZ, OMIG, OMDQ, OMIP, OMDU, OMDZ, OMDX, OMI1, OPPI, OMDW, OMDY, OMIA OMI2, OMI3, OMD0, OPPR, OX09, OMI8, OPPZ, OMIG, OMDQ, OMIP, OMDU, OMDZ, OMDX, OMI1, OPPI, OMDW, OMDY, OMIA, OMDT, OMI5, OMDC, OMIT, OMDR, OMIM, OMIN, OMIB, OMIR, OMDD, OMDV, OPPH, OMD3, OPPC, OMIL, OMIO, OMD2, OMIQ, OPPC, OMIL, OMIO, OMD2, OMIQ
Also refer
Frequently used database tables and customizing in MRP - ERP Manufacturing (PP) - SCN Wiki
Best Regards,
R.Brahmankar