### NBS_PUT_TRIGGER

Specify a routine to be called whenever a primitive item is updated

#### Description:

Check that the ID is not NIL and that it pertains to a primitive item.
Check that the caller owns the noticeboard (or WORLD_WRITE is TRUE).
Copy the address of the routine to be called on item update.

In this context "update" means any change to the item’s shape, data, size or modified count. The supplied routine is called with the following calling sequence:

TRIGGER (ID,STATUS)

where ID is the identifier of the item which has been altered and STATUS is as usual. Any bad status returned by the trigger routine will be passed back to the caller.

#### Invocation

(Int) = NBS_PUT_TRIGGER (ID,TRIGGER,STATUS)

#### Arguments

##### ID = INTEGER (Given)
Identifier of the item for which a trigger routine is to be specified.
##### TRIGGER = EXTERNAL (Given)
The address of the routine to call whenever the item is updated. From FORTRAN, declare it as EXTERNAL. Pass zero (requires %VAL(0) from FORTRAN) to disable the facility).
##### STATUS = INTEGER (Given and returned)
The global status. Possible return values are,
 NBS__NILID  NIL ID

 NBS__NOTOWNER  Caller does not own the noticeboard