| Name | Data Type | Definition | |
|---|---|---|---|
| BASE | string | 'Parent' airspace is the basis for subsequent operations. | |
| UNION | string | 'Parent' airspace is second operand in a union operation. | |
| INTERS | string | 'Parent' airspace is second operand in intersection operation. | |
| SUBTR | string | 'Parent' airspace is second operand in subtraction operation. | |
| OTHER | string | Other |