Technical Note 01-30, At the Core of the Data: The Address Table and Bit Table mentions the size of an allocation table (bit table) in the data file is 512 bytes, or 4 x 128 byte blocks of storage. Though the concept of the allocation table has not changed, and thus the Technical Note remains valid, the size of allocation tables has increased over time.
In 4D v11 SQL and 4D v12 allocation tables now occupy 2 KiB of storage, or 16 blocks of storage. This allows each allocation table to account for 2 MiB of data file storage instead of 512 KiB as in the Technical Note.
Note:1 Kib = 1024 bytes
1 MiB = 1048576 bytes