Moving TABKEY from CDPOS table into field structure in ABAP

I would suggest you make use of Function Module CHANGEDOCU_KEY_ANY2CHAR and other FM’s of function group SCD8. This function module performs the reverse function.

Function Module: CHANGEDOCU_KEY_ANY2CHAR

Function Group: SCD8

Program Name: SAPLSCD8

You can refer this SAP link to see all Function modules available and their description under this Function Group:

https://help.sap.com/viewer/c14d25a8f471453590980dbb47a2aa0e/7.40.15/en-US/48d8fd10f63a3e49e10000000a421937.html