| push [ valueExpression ] |
The pull instruction adds the value of valueExpression to the position in the external data queue that will be extracted next, by a parse pull or pull instruction. If valueExpression is absent, an empty line is added instead.
| queue [ valueExpression ] |
The queue instruction adds the value of valueExpression to the position in the external data queue that will be extracted last, by a parse pull or pull instruction. If valueExpression is absent, an empty line is added instead.