Chain identifiers are 4-byte values that follow a specific format:
The network-specific prefix: The first byte is used to identify the mainchain and its corresponding network of blockchains to which the chain wishes to establish a connection.
It is included explicitly to ensure that a chain does not use the same chain identifier in the test network as in the mainnet.
The chain-specific suffix: The other 3 bytes identify the chain within the network.
Must be unique within the network.