Introduction to the BDT

The Business data toolset (BDT) is a central control tool for maintaining SAP programs. It supports
maintenance via the use of dialog techniques, direct input and/or function modules.

The BDT is basically the tool SAP use when they want to add new fields, change field names, change/add
field groups etc for specific customers, but they are now starting to allow there customers access to these
maintenance transactions (i think mainly ramp-up customers at the moment).

Example use of the BDT can be found here  where it demonstrates how the BDT can be used to modify
the grants management master data transaction.