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— System Functions —

POS - Field Identification Function

Format/length:

The system function POS(field-name) contains the internal identification of the field whose name is specified with the system function.

POS(field-name) may be used to identify a specific field, regardless of its position in a map. This means that the sequence and number of fields in a map may be changed, but POS(field-name) will still uniquely identify the same field. With this, for example, you need only a single REINPUT statement to make the field to be MARKed dependent on the program logic.

Example:

DECIDE ON FIRST VALUE OF ... 
   VALUE ... 
      COMPUTE #FIELDX = POS(FIELD1) 
   VALUE ... 
      COMPUTE #FIELDX = POS(FIELD2) 
   ... 
END-DECIDE 
... 
REINPUT ... MARK #FIELDX

If the field specified with POS is an array, a specific occurrence must be specified; for example, POS(FIELDX(5)). POS cannot be applied to an array range.

POS and *CURS-FIELD

The system function POS(field-name) may be used in conjunction with the Natural system variable *CURS-FIELD to make the execution of certain functions dependent on which field the cursor is currently positioned in.

*CURS-FIELD contains the internal identification of the field in which the cursor is currently positioned; it cannot be used by itself, but only in conjunction with POS(field-name). You may use them to check if the cursor is currently positioned in a specific field and have processing performed depending on that condition.

Example:

IF *CURS-FIELD = POS(FIELDX) 
   MOVE *CURS-FIELD TO #FIELDY 
END-IF 
... 
REINPUT ... MARK #FIELDY

Notes:

The values of *CURS-FIELD and POS(field-name) serve only as internal identifications of the fields and cannot be used for arithmetic operations.
The value returned by POS(field-name) for an occurrence of an X-array (an array for which at least one bound in at least one dimension is specified as expansible) may change after the number of occurrences for a dimension of the array has been changed using the EXPAND, RESIZE or REDUCE statements.
Natural RPC: If *CURS-FIELD and POS(field-name) refer to a context variable, the resulting information can only be used within the same conversation.
In Natural for Ajax applications, *CURS-FIELD identifies the operand that represents the value of the control that has the input focus. You may use *CURS-FIELD in conjunction with the POS function to check for the control that has the input focus and perform processing depending on that condition.