+xThere are two ways for the user to deal with this.
FWIW, I have kept this post as a reference text and obviously support the suggestion of the checkmark to determine which situation applies. Many thanks for elaborating.
Setting up W&B for an Aquila 210, I am using method 1. The A210 empty weight includes unusable fuel. The mentioned disadvantage still exists (usable fuel entered as 'capacity' and zero entered for unusable) but, on the other hand, the volume I enter while planning corresponds to what the dip stick and gauges indicate.
Both indicators are calibrated to show empty when the tanks hold just the amount of unusable fuel. The dip stick resembles a T bar hanging from the upper wing surface, as opposed to resting on the tank bottom. The fuel gauges are calibrated as mentioned per maintenance manual. The only remaining complication is that 54.8 liters per tank require more brain capacity for quick calculations than 60 would. ;-)