When choosing a value for R6, ensure that Q2's base-emitter voltage is less than approximately 0.5V at the maximum permissible value of the load current.
In the event of an overload when ILOAD exceeds its maximum permissible value, the increase in voltage across R6 results in sufficient base-emitter voltage to turn on Q2.
An example of this is properties whose domain (the collection of permissible values for the property) is people.
These literals may be datatyped, so you could define a W3C XML Schema enumeration to govern the permissible values (see Resources).
