Receiver interrupt masked request
| TRIGGER | Logical and of corresponding request and mask bits. |
| NOT_EMPTY | Logical and of corresponding request and mask bits. |
| FULL | Logical and of corresponding request and mask bits. |
| OVERFLOW | Logical and of corresponding request and mask bits. |
| UNDERFLOW | Logical and of corresponding request and mask bits. |
| BLOCKED | Logical and of corresponding request and mask bits. |
| FRAME_ERROR | Logical and of corresponding request and mask bits. |
| PARITY_ERROR | Logical and of corresponding request and mask bits. |
| BAUD_DETECT | Logical and of corresponding request and mask bits. |
| BREAK_DETECT | Logical and of corresponding request and mask bits. |