Vector: Selects if 3D points should be represented in the usual (x,y,z) Cartesian form or in the Polar coordinate form (heading, pitching, radius). In the latter form, heading defines the projected direction in the horizon plane and pitching defines the angle with the horizon plane. Radius is the distance from the origin.
|Y = up axis is the native system. All data is internally stored this way. Scripting languages and other low level systems always access the data in the native form.|
Decimals: The number of displayed decimal units for all floating point gadgets in the program. For example, a value 1.238 is displayed as 1.24 if decimals is set to two. Note that this does not round the actual value: you can enter floating point values with as many decimals as you like, and they are all taken into account. Note also that the amount of decimals is independent from the measuring unit. Two decimals may be sufficient if you are using millimeters, but 4-5 is more appropriate when using meters.
Three fields: If set, 3D coordinate gadgets consist of three separate sub fields. Then each sub coordinate can be adjusted separately with the dial control and the mouse. Also, changing one coordinate only (leaving two other intact) for a set of selected objects is easier.