Define here the number of decimal figures used to show the most important 
types of real data. This is not related with the precision used internally, 
which is always the maximum possible (double precision).
Digits
The number of decimal figures used to show 
Length,                   
Angle, 
Mass and 
Charge real values is 
defined here. This includes everything related with these 
types of data, from atom radius to light position, from
cell angles to rotation step.
Less important types of real data, such as light attenuation 
or color components, have default values, defined at compile time.