'Smart' X10 and other X10 capable dimmers have the ability to remember the Preset value and will return to that when the next ON is received or the switch is turned on manually. This is a nice feature for setting the ON level at different times. For example you might change an overhead light level to a nightlight level after bedtime and return it to full on after breakfast time. Then a motion sensor controlling that light would not have to alter it's behavior at all, just send an ON and the light would go to the proper level for the time and state of the house.
XTension offers a feature which will simulate the same effect with even the 'dumb' dimmers that are most commonly and inexpensively available.
In general, XTension remember this 'preset level' in the database with the other Unit variables and provides methods of changing this preset value. In order to setup such a Unit, you should simply set the options in the Edit Unit dialog: Dimmable and Simulated
You have three different methods of setting the 'preset level'.
example: sim preset “Office Lights” to 25
Once the 'preset level' is set, all you do from then on to control the Unit is to use the ON and OFF commands.
XTension will always DIM the Unit to Zero for an OFF command, and will Brighten the Unit to the Preset level for an ON command.
The idea is that YOU determine what your preference for the level is at different times of day (MODE of the home?) and thereafter all scripts that control the Unit need only issue ON or OFF commands.
This saves a lot of time and scripting and turns those old Dumb dimmers into reasonably well-behaved 'almost smart' dimmers.