A reference configuration of the transmission chain is shown in GSM 05.01 [4]. According to this reference configuration@ the present document specifies the data blocks given to the encryption unit. It includes the specification of encoding@ reordering@ interleaving and the stealing flag. It does not specify the channel decoding method. The definition is given for each kind of logical channel@ starting from the data provided to the channel encoder by the speech coder@ the data terminal equipment@ or the controller of the Mobile Station (MS) or Base Transceiver Station (BTS). The definitions of the logical channel types used in this technical specification are given in GSM 05.02 [5]@ a summary is in annex A.