Per ATIS-0300119, Thousands-Block (NPA-NXX-X) & Central Office Code (NPA-NXX) Administration Guidelines (TBCOCAG), Section 11.1.5, “When the CO Code is a Non-pooled CO Code the SP shall build the records for any Thousands-Blocks being retained on the NXD-A screen after the NANPA has approved the disconnect. At the time the NANPA processes the disconnect the NANPA shall update the BCR record in BIRRDS with the Effective Date indicated on the Part 3.” 

Any Thousands-Block within the CO Code that has been retained, your AOCN needs to go into BIRRDS and create the NXD-X records. For example, if you disconnect/donated NPA-NXX, Block 1, 2 and 3, your AOCN would need to create the NXD-X records for NPA-NXX Block 0, 4, 5, 6, 7, 8 and 9.