Once the Thousands-Blocks have been assigned to you, then you can submit a block modification request in NAS and select ‘Part 1B’ as the type of change, then indicate “Yes” on the Part 1B for ‘Will block X of X be activated by NPAC’ and “No” on the Part 1B for “Is block being allocated back to the code holder on the switch where the NXX Code Resides”.