ic operations (or are based on such operations), special graphical symbols are defined. One example of such an interface is the SAP. Since a SAP represents an interface for data flows, the basic operations in a SAP are some type of send and receive operations. Operations that help control the data flow might exist as well, like flow-control operations, 10 There are ten primitive types: Request, Confirm, Refuse, Order, Reject, Offer, Invite, ReportInit, ReportConfirm and ReportRefuse. 11 There are 6 operation classes: REQUEST, ORDER, OFFER, INVITE, C_REPORT, U REPORT (short versions: REQ, ORD, OFF, INV, C REP, U_REP). 3 Logical Network Modelling reset operations, etc., but AML offers no generic operations for those. Note also that the use of generic operations is in no way mandatory for the AML user. The names and some basic parameters of generic send and receive operations are chosen to reflect the basic set of CSPs, see Fig. 3.26. SAP type Basic operation name Basic parameters sendInfo reclnfo sendCn STU, USU recCn sendCon CEI, SDU recCon sendCnl destSAPI, SDU, QoS recCnl origSAPI, SDU CEI connection endpoint Identifier SDU service data unit QoS quality of service parameters SIU service information unit SAPI service access point STU structured data unit destSAPI destination SAPI USU unstructured data unit origSAPI originating SAPI Fig. 3.26 Operation name classification in SAPs An important property of receive operations is the way the CSP can discriminate between many received SDUs that are not yet delivered to the CSP user. Figure 3.27 describes the major cases of discrimination in this respect (sometimes called selective receive), separated into CON and CNL types of SAPs. General receive, CON: General receive, CNL: recConRequest() recCnlRequest() recConConfirm(CEI,SDU,...) recCnIConfirm(sender SAPI,SDU,...) recConRefuse() recCnlRefuse() Addressed receive, CON: Specific receive, CNL: recConRequest(CEI,...) recCnIRequest(sender SAPI) recConConfirm(SDU,,..) recCnIConfirm(SDU,... recConRefuse() recCnlRefuse() Spe