This type is used as a request identifier. It also serves as a success indicator; the value can be tested using the rascal_isok function to see if the requested operation was successfully scheduled or performed. If the result is negative, then the corresponding error description can be retrieved using the rascal_get_errmsg function.

Request identifiers can be used to cancel a request that was scheduled for background execution. However, not every operation can be cancelled; an example of one that can't be is rascal_write. Typically, a manifest constant REC_SUCCESS is returned when the request was successfully scheduled but can not be cancelled.