- Permissible Code Groups （许用码组）
- Coding that follow the requirement.
- Forbidden Code Groups （禁用码组）
- Vice.
- A code with minimum distance d between its codewords can detect at most d-1 errors and can correct (d-1)/2 errors
Cyclic Coding
(n, k): ‘n’ is the length of the codeword (the message after it has been encoded), and ‘k’ is the length of the original message before encoding.