Editing Aztec Code (section)

=== Check codewords ===
Both the mode word, and the data, must have check words appended to fill out the available space.  This is computed by appending ''K'' check words such that the entire message is a multiple of the Reed–Solomon polynomial (''x''−2)(''x''−4)...(''x''−2<sup>''K''</sup>).

Note that check words are ''not'' subject to bit stuffing, and may be all-zero or all-one.  Thus, it is not possible to detect the erasure of a check word.