An apparatus and a method for adapting data in a communications system to be transmitted from a sender to a receiver, to a transport unit of a predefined size involve representing said data as a combination of bits over a finite field, wherein said data comprises of an information part and a control part; adapting said represented data to fit said predefined size of said transport unit, by expressing both said information and control parts with bits, wherein said bits are less in number that said represented combination of bits and a number of removed bits is known to said receiver, said removed bits comprise of bits from both said information and control parts.