Use of FM /SAPAPO/TS_DM_SET in SCM APO 4 ?

Hello

In APO to change the Key figure value in Planning Book we can use 'BAPI_PBSRVAPS_CHANGEKEYFIGVAL' , I understand as well , FM /SAPAPO/TS_DM_SET can also be used to change the Key figure in the Planning Book.

Please let me know if some one knows the difference between

1. FM /SAPAPO/TS_DM_SET

2. 'BAPI_PBSRVAPS_CHANGEKEYFIGVAL'

and also how to use FM -FM /SAPAPO/TS_DM_SET ?

Your inputs in this regard are much appreciated ..

Thank you - Prasad.