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


T_OPTDATA_IND - Data indication with options


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

struct T_optdata_ind {
    t_scalar_t PRIM_type;      /* always T_OPTDATA_IND           */
    t_scalar_t DATA_flag;      /* flag bits associated with data */
    t_scalar_t OPT_length;     /* options length                 */
    t_scalar_t OPT_offset;     /* options offset                 */


The primitive indicates to the transport user that the message contains a transport interface data unit. One or more transport interface data units form a transport service data unit (TSDU).

Note that the maximum transport service and data unit sizes allowed by a transport provider is indicated to the user by the T_INFO_ACK primitive.

This primitive has a mechanism that 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.

This primitive also provides mechanisms to have options associated with the data being transferred.


The fields of this message have the following semantics:


identifies the primitive type


specifies bit fields specific general properties associated with the data being transferred. The following settings are currently defined:

When set, this bit indicates that the next T_OPTDATA_IND primitive is also part of this transport service data unit.


the length of the requested options asociated with the primitive


the offset (from the beginning of the M_PROTO message block) where the options asociated with this primitive begin.


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


Only connection mode.


Transport provider.

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