| AbstractEnum | A general enum implementation until we got SplEnum. |
| BitArray | A simple, fast array of bits. |
| BitMatrix | Bit matrix. |
| BitUtils | General bit utilities. |
| CharacterSetEci | Encapsulates a Character Set ECI, according to "Extended Channel Interpretations" 5.3.1.1 of ISO 18004. |
| EcBlock | Encapsualtes the parameters for one error-correction block in one symbol version. This includes the number of data codewords, and the number of times a block with these parameters is used consecutively in the QR code version's format. |
| EcBlocks | Encapsulates a set of error-correction blocks in one symbol version. Most versions will use blocks of differing sizes within one version, so, this encapsulates the parameters for each set of blocks. It also holds the number of error-correction codewords per block since it will be the same across all blocks within one version. |
| ErrorCorrectionLevel | Enum representing the four error correction levels. |
| FormatInformation | Encapsulates a QR Code's format information, including the data mask used and error correction level. |
| Mode | Enum representing various modes in which data can be encoded to bits. |
| ReedSolomonCodec | Reed-Solomon codec for 8-bit characters. |
| Version | Version representation. |
