Compaq ACMS for OpenVMS
ADU Reference Manual
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ACMS starts an Rdb transaction that can read data in the EMPLOYEES relation, and that can store, modify, and erase data in the SALARY_HISTORY and JOBS relations. EXCLUSIVE specifies that no other users can access a relation while you are working with it; SHARED specifies that other users can work with a relation while you are working with it; READ specifies that you can only read data in a relation; and WRITE specifies that you can store, modify, or erase data in a relation. You do not use a semicolon (;) after the DML string because RDB RECOVERY is a phrase rather than a clause.
#3 

GET_EMPLOYEE_ID_TASK 
  DEFAULT SERVER IS EMPLOYEE_SERVER; 
  BLOCK WORK WITH FORM I/O 
                  RDB RECOVERY 
    "START_TRANSACTION READ_WRITE RESERVING EMPLOYEES FOR 
                                  PROTECTED WRITE" 
    EXCHANGE 
      RECEIVE FORM RECORD GET_EMPLOYEE_ID_RECORD 
        RECEIVING EMPLOYEE_ID_WKSP; 
 
    PROCESSING 
      CALL GET_EMPLOYEE_INFO 
        USING EMPLOYEE_ID_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     : RETAIN SERVER CONTEXT; 
                  RETAIN RECOVERY UNIT; 
                  GOTO NEXT STEP; 
        "B"     : ROLLBACK; 
                  CANCEL TASK; 
      END CONTROL FIELD; 
 
    EXCHANGE 
      SEND FORM RECORD GET_EMPLOYEE_ID_RECORD 
        SENDING EMPLOYEE_ID_WKSP 
        WITH RECEIVE CONTROL QUIT_WORKSPACE; 
      CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
        " FEXT"   :    ROLLBACK; 
                       EXIT TASK; 
      END CONTROL FIELD; 
 
    PROCESSING 
      CALL WRITE_EMPLOYEE_INFO 
        USING EMPLOYEE_ID_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     : COMMIT; 
        "B"     : ROLLBACK; 
                  CANCEL TASK; 
      END CONTROL FIELD; 
  END BLOCK; 
END DEFINITION;

In this example definition, the user retrieves and modifies information about an employee. The Rdb transaction is specified on the block step. If the operation fails (either in retrieving or updating the information), the transaction is rolled back; otherwise, the updates are committed. Note that server context and the recovery unit are retained after the first processing step.

Processing Phrase Examples

#1 

PROCESSING WITH 
  RDB RECOVERY "START_TRANSACTION READ_WRITE RESERVING " & 
    "DEPART FOR SHARED READ, ADMIN FOR PROTECTED WRITE"

This DML string starts a read-write database transaction, allowing read- only access to the DEPART relation and protected write access to the ADMIN relation. No other relations are available for access.

#2 

PROCESSING WITH RDB RECOVERY 
  "START_TRANSACTION READ_WRITE RESERVING EMPLOYEES 
                     FOR SHARED WRITE"

ACMS starts a recovery unit for a transaction that can store, modify, and erase data in the EMPLOYEES relation. SHARED specifies that other users can work with the EMPLOYEES relation while you are working with it, and WRITE specifies that you can store, modify, or erase data in the relation. You do not use a semicolon (;) after the database string because RDB RECOVERY is a phrase rather than a clause.

#3 

GET_EMPLOYEE_ID_TASK 
  DEFAULT SERVER IS EMPLOYEE_SERVER; 
  BLOCK WORK WITH FORM I/O 
    EXCHANGE 
       RECEIVE FORM RECORD GET_EMPLOYEE_ID_RECORD 
         RECEIVING EMPLOYEE_ID_WKSP 
         WITH RECEIVE CONTROL QUIT_WORKSPACE; 
       CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY   
         " FEXT"  :  EXIT TASK; 
       END CONTROL FIELD; 
 
    PROCESSING WITH RDB RECOVERY 
      "START_TRANSACTION READ_WRITE RESERVING EMPLOYEES 
                         FOR SHARED WRITE" 
       CALL GET_EMPLOYEE_INFO 
         USING EMPLOYEE_ID_WKSP; 
       CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     :  RETAIN SERVER CONTEXT; 
                   RETAIN RECOVERY UNIT; 
                   GOTO NEXT STEP; 
        "B"     :  ROLLBACK; 
                   GOTO PREVIOUS TASK; 
       END CONTROL FIELD; 
 
    EXCHANGE 
      SEND FORM RECORD GET_EMPLOYEE_ID_RECORD 
        SENDING EMPLOYEE_ID_WKSP 
        WITH RECEIVE CONTROL QUIT_WORKSPACE; 
      CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
        " FEXT"   :    ROLLBACK; 
                       CANCEL TASK; 
      END CONTROL FIELD; 
 
    PROCESSING 
       CALL WRITE_EMPLOYEE_INFO 
         USING EMPLOYEE_ID_WKSP; 
       CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     :  COMMIT; 
        "B"     :  ROLLBACK; 
                   CANCEL TASK; 
       END CONTROL FIELD; 
  END BLOCK; 
END DEFINITION;

In this example, the user retrieves and modifies information about an employee. The Rdb transaction is specified on the first processing step. If the information about the employee cannot be retrieved, the transaction is rolled back and the initial exchange is repeated. If the update fails, the transaction is rolled back and the task is canceled. Note that server context and the recovery unit are retained after the first processing step.

REPEAT TASK Clause (Action)

Ends the current task instance and restarts the task without requiring the terminal user to select the task from a menu.

Format

REPEAT TASK [ PASSING workspace-name [,...] ] ;

Parameter

workspace-name

The name of the workspace you want to pass from the current task instance to the new task instance.

Clause Default

If you do not use the REPEAT TASK clause, ACMS does not repeat the task. The default sequencing action for a step within a root block is GOTO NEXT STEP. The default sequencing action for a root block or a processing step in a single-step task is EXIT TASK.

Notes

You cannot specify the REPEAT TASK clause in the action part of a step within a distributed transaction. If you specify REPEAT TASK on a root block, that task cannot be called by a parent task to participate in a distributed transaction.

When you use the REPEAT TASK clause in a step that does not start a distributed transaction, the default recovery action is COMMIT IF ACTIVE RECOVERY UNIT and the default context action is RELEASE SERVER CONTEXT IF ACTIVE SERVER CONTEXT.

If you use the REPEAT TASK clause, you cannot declare the following clauses in the same action specification:

When you chain from one task to another, ACMS reinitializes any task workspaces not passed.

Example


WORKSPACES ARE ADD_EMPLOYEE_WKSP, QUIT_WORKSPACE; 
BLOCK WITH FORM I/O 
  EXCHANGE 
    RECEIVE FORM RECORD ADD_EMPLOYEE_RECORD 
      RECEIVING ADD_EMPLOYEE_WKSP 
      WITH RECEIVE CONTROL QUIT_WORKSPACE; 
    CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
      " FCAN"   :  CANCEL TASK; 
    END CONTROL FIELD; 
  PROCESSING 
    CALL PERSADD IN PERSONNEL USING ADD_EMPLOYEE_WKSP; 
    CONTROL FIELD ACMS$T_STATUS_TYPE 
      "B"        : GET ERROR MESSAGE; 
                   GOTO PREVIOUS EXCHANGE; 
    END CONTROL FIELD; 
  END BLOCK WORK; 
  REPEAT TASK; 
END DEFINITION;

This data entry task adds a new employee record to a file. Because this is a task a user would like to repeat without having to reselect the task from a menu, you include the REPEAT TASK clause in the action part of the block step definition.

RETAIN RECOVERY UNIT Clause (Action)

Maintains the recovery unit within the current server.

Format

RETAIN RECOVERY UNIT [ IF ACTIVE RECOVERY UNIT ] ;

Keyword

IF ACTIVE RECOVERY UNIT

Retains the recovery unit only if there is an active recovery unit. If you use the IF ACTIVE RECOVERY UNIT keywords, and there is no active recovery unit, ACMS does not attempt to retain a recovery unit. If you do not use the IF ACTIVE RECOVERY UNIT keywords, and there is no active recovery unit when you use the RETAIN RECOVERY UNIT clause, ACMS cancels the task.

Clause Default

The RETAIN RECOVERY UNIT clause is optional.

Table 7-3 shows the default recovery actions for a task.

Notes

You can use the RETAIN RECOVERY UNIT clause only in the action specifications of steps within a block.

Example


BLOCK 
  WORK WITH FORM I/O 
  GET_DEPT_NUMBER: 
    EXCHANGE 
      RECEIVE FORM RECORD REVIEW_SCHEDULE 
        RECEIVING REVIEW_SCHEDULE_WKSP 
        WITH RECEIVE CONTROL QUIT_WORKSPACE; 
      CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
        " FCAN"   : CANCEL TASK; 
      END CONTROL FIELD; 
 
  GET_FIVE_EMPLOYEES: 
    PROCESSING WITH 
      DBMS RECOVERY "READY ADMIN DEPART CONCURRENT RETRIEVAL" 
      CALL REVIEW_SCHEDULE_GET IN DEPARTMENT_SERVER 
        USING REVIEW_SCHEDULE_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "B"        : GET ERROR MESSAGE; 
                     GOTO PREVIOUS EXCHANGE; 
        "G"        : RETAIN RECOVERY UNIT; 
                     RETAIN SERVER CONTEXT; 
                     GOTO NEXT STEP; 
      END CONTROL FIELD;

If the REVIEW_SCHEDULE_GET procedure is successful in retrieving review schedule information for a department, ACMS returns the value "G" to the ACMS$T_STATUS_TYPE field of the ACMS$PROCESSING_STATUS system workspace. In this task, the user can choose to look at the next five records in the file. Therefore, you want to retain currency indicators to maintain the user's file location. Use the RETAIN RECOVERY UNIT clause to maintain that recovery unit.

RMS RECOVERY Phrase (Block, Processing)

Starts an RMS recovery unit for a block or processing step.

Format

RMS RECOVERY

Phrase Default

The RMS RECOVERY phrase is optional. If you do not include it, ACMS does not start an RMS recovery unit.

Notes

You can use the RMS RECOVERY phrase only when defining a processing step or block step. When you use the RMS RECOVERY phrase at the start of a processing step or block step, ACMS sets the default recovery action for that step to COMMIT IF ACTIVE RECOVERY.

You cannot use the RMS RECOVERY phrase in a processing step that runs in a DCL server.

If you use the RMS RECOVERY phrase and the NO PROCESSING clause in the same processing step, ACMS cancels the task.

You must use separate servers for DBMS, Rdb, RMS, and SQL procedures if you are using recovery units with more than one of these products in the same application. Only one type of recovery unit can be used for each server or step.

You cannot specify the RMS RECOVERY phrase on a nested block.

You cannot specify more than one recovery statement (RDB, DBMS, RMS, or SQL) for the same block or processing step.

Table 7-3 shows the default recovery actions for different situations in a task definition.

Table 7-3 Default Recovery Actions
  Default Recovery Action
   
Action Clause If you started the recovery unit in the current step If you did not start the recovery unit in the current step
  • CANCEL TASK
  • RAISE EXCEPTION
ROLLBACK IF ACTIVE RECOVERY UNIT ROLLBACK IF ACTIVE RECOVERY UNIT
  • EXIT TASK,
  • GOTO TASK,
  • REPEAT TASK,
  • RELEASE CONTEXT,
  • RELEASE CONTEXT
  • IF ACTIVE
  • RECOVERY UNIT
COMMIT IF ACTIVE RECOVERY UNIT COMMIT IF ACTIVE RECOVERY UNIT
  • OTHER
COMMIT IF ACTIVE RECOVERY UNIT NO RECOVERY UNIT ACTION

Block Phrase Examples

#1 

BLOCK WITH RMS RECOVERY

ACMS starts an RMS recovery unit for the transaction. You do not use a semicolon (;) because RMS RECOVERY is a phrase, not a clause.

#2 

GET_EMPLOYEE_ID_TASK 
  DEFAULT SERVER IS EMPLOYEE_SERVER; 
 
  BLOCK WORK WITH FORM I/O 
                  RMS RECOVERY 
 
    EXCHANGE 
      RECEIVE FORM RECORD GET_EMPLOYEE_ID_RECORD 
        RECEIVING EMPLOYEE_ID_WKSP; 
 
    PROCESSING 
      CALL GET_EMPLOYEE_INFO 
        USING EMPLOYEE_ID_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     : RETAIN SERVER CONTEXT; 
                  RETAIN RECOVERY UNIT; 
                  GOTO NEXT STEP; 
        "B"     : ROLLBACK; 
                  CANCEL TASK; 
      END CONTROL FIELD; 
 
    EXCHANGE 
      SEND FORM RECORD GET_EMPLOYEE_ID_RECORD 
        SENDING EMPLOYEE_ID_WKSP 
        WITH RECEIVE CONTROL QUIT_WORKSPACE; 
      CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
        " FEXT"   :    ROLLBACK; 
                       EXIT TASK; 
      END CONTROL FIELD; 
 
    PROCESSING 
      CALL WRITE_EMPLOYEE_INFO 
        USING EMPLOYEE_ID_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     : COMMIT; 
        "B"     : ROLLBACK; 
                  CANCEL TASK; 
      END CONTROL FIELD; 
  END BLOCK; 
END DEFINITION;

In this example definition, the user retrieves and modifies information about an employee. The RMS transaction is specified in the block step. If the operation fails (either in retrieving or updating the information), the transaction is rolled back; otherwise, the updates are committed.

Note that server context and the recovery unit are retained after the first processing step.

Processing Phrase Examples

#1 

PROCESSING WITH RMS RECOVERY

ACMS starts a recovery unit for the transaction. You do not use a semicolon (;) because RMS RECOVERY is a phrase rather than a clause.

#2 

GET_EMPLOYEE_ID_TASK 
  DEFAULT SERVER IS EMPLOYEE_SERVER; 
  BLOCK WORK WITH FORM I/O 
    EXCHANGE 
       RECEIVE FORM RECORD GET_EMPLOYEE_ID_RECORD 
         RECEIVING EMPLOYEE_ID_WKSP 
         WITH RECEIVE CONTROL QUIT_WORKSPACE; 
       CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY   
         " FEXT"  :  EXIT TASK; 
       END CONTROL FIELD; 
 
    PROCESSING WITH RMS RECOVERY 
       CALL GET_EMPLOYEE_INFO 
         USING EMPLOYEE_ID_WKSP; 
       CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     :  RETAIN SERVER CONTEXT; 
                   RETAIN RECOVERY UNIT; 
                   GOTO NEXT STEP; 
        "B"     :  ROLLBACK; 
                   GOTO PREVIOUS TASK; 
       END CONTROL FIELD; 
 
    EXCHANGE 
      SEND FORM RECORD GET_EMPLOYEE_ID_RECORD 
        SENDING EMPLOYEE_ID_WKSP 
        WITH RECEIVE CONTROL QUIT_WORKSPACE; 
      CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
        " FEXT"   :    ROLLBACK; 
                       CANCEL TASK; 
      END CONTROL FIELD; 
 
    PROCESSING 
       CALL WRITE_EMPLOYEE_INFO 
         USING EMPLOYEE_ID_WKSP; 
       CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     :  COMMIT; 
        "B"     :  ROLLBACK; 
                   CANCEL TASK; 
       END CONTROL FIELD; 
  END BLOCK; 
END DEFINITION;

In this example definition, the user retrieves and modifies information about an employee. The RMS transaction is specified in the first processing step. If the information about the employee cannot be retrieved, the transaction is rolled back and the initial exchange is repeated. If the update fails, the transaction is rolled back and the task is canceled.

Note that server context and the recovery unit are retained after the first processing step.

ROLLBACK Clause (Action)

Signals the end of a recovery unit, returning (rolling back) all recoverable objects to the state they were in at the beginning of the current recovery unit.

Format

ROLLBACK [ IF ACTIVE RECOVERY UNIT ] ;

Keywords

IF ACTIVE RECOVERY UNIT

Performs a ROLLBACK only if there is an active recovery unit. If you use the IF ACTIVE RECOVERY UNIT keywords, and there is no active recovery unit, ACMS does not attempt to roll back a database transaction. If you do not use the IF ACTIVE RECOVERY UNIT keywords, and there is no active recovery unit when you use the ROLLBACK clause, ACMS cancels the task.

Clause Default

The ROLLBACK clause is optional.

Table 7-3 shows the default recovery actions for a task.

Example


BLOCK WITH FORM I/O 
  GET_DEPT_NUMBER: 
    EXCHANGE 
      RECEIVE FORM RECORD REVIEW_SCHEDULE 
        RECEIVING REVIEW_SCHEDULE_WKSP 
        WITH RECEIVE CONTROL QUIT_WORKSPACE; 
      CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
        " FCAN"   : CANCEL TASK; 
      END CONTROL FIELD; 
 
  GET_FIVE_EMPLOYEES: 
    PROCESSING WITH 
      DBMS RECOVERY "READY CONCURRENT UPDATE" 
      CALL REVIEW_SCHEDULE_GET IN DEPARTMENT_SERVER 
        USING REVIEW_SCHEDULE_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "B"        : GET ERROR MESSAGE; 
                     ROLLBACK; 
                     RELEASE SERVER CONTEXT; 
                     GOTO PREVIOUS EXCHANGE; 
        "G"        : RETAIN RECOVERY UNIT; 
                     NO CONTEXT ACTION; 
                     GOTO NEXT STEP; 
      END CONTROL FIELD;

If the REVIEW_SCHEDULE_GET procedure is successful in retrieving review schedule information for a department, ACMS returns the value "G" to the ACMS$T_STATUS_TYPE field of the ACMS$PROCESSING_STATUS system workspace. In this task, the user can choose to look at the next five records in the file. Therefore, you want to retain currency indicators to maintain the user's file location. However, you do not want to retain these currency indicators if the procedure is unsuccessful. Use the ROLLBACK clause to return the database to the state it was in at the start of the recovery unit.

SQL RECOVERY Phrase (Block, Processing)

Starts an SQL transaction with an Rdb database or a VIDA database at the beginning of a block or processing step. If you use the SQL RECOVERY phrase to start your transaction, you must end your transaction with a COMMIT or ROLLBACK clause.

Format

SQL RECOVERY dml-string [,...]

Parameter

dml-string

The Data Manipulation Language (DML) string is a DML statement with which you start an SQL transaction at the block or processing step level. The DML string can contain any legal SET TRANSACTION syntax, including the characteristics you want to apply to the transaction. Use the DML RESERVING clause to apply different characteristics to different relations.

ADU supports DML strings up to a length of 255 characters.

When you enter strings longer than 255 characters into ADU, ACMS issues a warning, and the string is truncated. To overcome this restriction, put SQL RECOVERY statements in procedure servers rather than in task definitions.

For more information on DML strings, refer to the SQL documentation.

Phrase Default

The SQL RECOVERY phrase is optional. If you do not include it or the RDB RECOVERY phrase, ACMS does not start an RDB database transaction.

Notes

ACMS calls SQL$INTERPRET to execute the DML statement that you supply to start the database transaction. Starting an update transaction creates a recovery unit. To use the SQL RECOVERY phrase, you must bind the database in the server initialization procedure.

Use the SQL RECOVERY phrase only when defining a processing step or block step. When you use the SQL RECOVERY phrase at the start of a processing step or block step, ACMS sets the default recovery action for that step to COMMIT IF ACTIVE RECOVERY.

You cannot use the SQL RECOVERY phrase in a processing step that runs in a DCL server.

If you use the SQL RECOVERY phrase and the NO PROCESSING clause in the same processing step, ACMS cancels the task.

You must use separate servers for DBMS, Rdb, RMS, and SQL procedures if you are using recovery units with more than one of these products in the same application. Only one type of recovery unit can be used for each server or step. You cannot specify more than one recovery statement (SQL, RDB, DBMS, or RMS) for the same block or processing step. Table 7-4 shows the default recovery actions for different situations in a task definition.

Table 7-4 Default Recovery Actions
  Default Recovery Action
   
Action Clause If you started the recovery unit in the current step If you did not start the recovery unit in the current step
  • CANCEL TASK
  • RAISE EXCEPTION
ROLLBACK IF ACTIVE RECOVERY UNIT ROLLBACK IF ACTIVE RECOVERY UNIT
  • EXIT TASK,
  • GOTO TASK,
  • REPEAT TASK,
  • RELEASE CONTEXT,
  • RELEASE CONTEXT
  • IF ACTIVE
  • RECOVERY UNIT
COMMIT IF ACTIVE RECOVERY UNIT COMMIT IF ACTIVE RECOVERY UNIT
  • OTHER
COMMIT IF ACTIVE RECOVERY UNIT NO RECOVERY UNIT ACTION

Block Phrase Examples

#1 

BLOCK WITH SQL RECOVERY 
  "SET TRANSACTION READ WRITE RESERVING EMPLOYEES FOR SHARED WRITE"

ACMS starts an SQL transaction that can store, modify, and erase data in the EMPLOYEES table. SHARED specifies that other users can work with the EMPLOYEES relation while you are working with it, and WRITE specifies that you can store, modify, or erase data in the table. Do not use a semicolon (;) after the database string because SQL RECOVERY is a phrase rather than a clause.

#2 

BLOCK WITH SQL RECOVERY                                        
  "SET TRANSACTION READ WRITE RESERVING "       & 
              "EMPLOYEES FOR SHARED READ, "       & 
              "SALARY_HISTORY FOR SHARED WRITE, " & 
              "JOBS FOR EXCLUSIVE WRITE"

ACMS starts an SQL transaction that can read data in the EMPLOYEES table, and store, modify, and erase data in the SALARY_HISTORY and JOBS tables. EXCLUSIVE specifies that no other users can access a table while you are working with it; SHARED specifies that other users can work with a table while you are working with it; READ specifies that you can only read data in a table; and WRITE specifies that you can store, modify, or erase data in a table. You do not use a semicolon (;) after the DML string because SQL RECOVERY is a phrase rather than a clause.

#3 

GET_EMPLOYEE_ID_TASK 
  DEFAULT SERVER IS EMPLOYEE_SERVER; 
  BLOCK WORK WITH 
             FORM I/O 
             SQL RECOVERY 
    "SET TRANSACTION READ WRITE 
         RESERVING EMPLOYEES FOR PROTECTED WRITE" 
    EXCHANGE 
      RECEIVE FORM RECORD GET_EMPLOYEE_ID_RECORD 
        RECEIVING EMPLOYEE_ID_WKSP; 
 
    PROCESSING 
      CALL GET_EMPLOYEE_INFO 
        USING EMPLOYEE_ID_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     : RETAIN SERVER CONTEXT; 
                  RETAIN RECOVERY UNIT; 
                  GOTO NEXT STEP; 
        "B"     : ROLLBACK; 
                  CANCEL TASK; 
      END CONTROL FIELD; 
 
    EXCHANGE 
      SEND FORM RECORD GET_EMPLOYEE_ID_RECORD 
        SENDING EMPLOYEE_ID_WKSP 
        WITH RECEIVE CONTROL QUIT_WORKSPACE; 
      CONTROL FIELD IS QUIT_WORKSPACE.QUIT_KEY 
        " FEXT"   :    ROLLBACK; 
                       EXIT TASK; 
      END CONTROL FIELD; 
 
    PROCESSING 
      CALL WRITE_EMPLOYEE_INFO 
        USING EMPLOYEE_ID_WKSP; 
      CONTROL FIELD ACMS$T_STATUS_TYPE 
        "G"     : COMMIT; 
        "B"     : ROLLBACK; 
                  CANCEL TASK; 
      END CONTROL FIELD; 
  END BLOCK; 
END DEFINITION;

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