| Attribute | Description | Type |
| if | Sets the property name for the 'if' condition. The define will be ignored unless the property is defined. The value of the property is insignificant, but values that would imply misinterpretation ("false", "no") will throw an exception when evaluated. | String |
| name | Set the name attribute | String |
| unless | Set the property name for the 'unless' condition. If named property is set, the define will be ignored. The value of the property is insignificant, but values that would imply misinterpretation ("false", "no") of the behavior will throw an exception when evaluated. | String |
| value | Set the value attribute | String |