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Transport Provider Interface (TPI), Version 2 Draft 2
Copyright © 1999 The Open Group


T_DATA_IND - Data Indication


This message consists of one M_PROTO message block followed by zero or more M_DATA message blocks where each M_DATA message block contains at least one byte of data. The format of the M_PROTO message block is as follows:

struct T_data_ind {
    t_scalar_t   PRIM_type;      /* Always T_DATA_IND */
    t_scalar_t   MORE_flag;


This primitive indicates to the transport user that this message contains a transport interface data unit. One or more transport interface data units form a transport service data unit. This primitive has a mechanism which indicates the beginning and end of a transport service data unit. However, not all transport providers support the concept of a transport service data unit.


identifies the primitive type.


when greater than zero, indicates that the next T_DATA_IND primitive is also part of this transport service data unit.


If a TSDU spans multiple T_DATA_IND message blocks, then an ETSDU may be placed in between two T_DATA_IND message blocks. Once an ETSDU is started, then the ETSDU must be completed before any T_DATA_IND message blocks defining a TSDU is resumed.


Only connection-mode.


Transport provider.

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