Hello
Depends on the version and MCU you are using.
Once you are connected to the board enter command FLASH. This will list all Non volatile Memory block available.
The block number is also specified in there.
For more information on AEFSKIPERASING look at {Install}\help\PDF\Debugger_HC12.pdf Chapter "Book IV Commands and environment Variables" section ""Connection-Specific Commands" -> "NMVC commands" (on V4.7 installation layout).
You can also find information in {Install}\Release_Notes\HC12\Notes_debugger_P&E_Multilink_Cyclone_Pro.txt (also from V4.7 installation layout).
I hope this helps.
CrasyCat