Units:
    Silo can operate in either the English (feet and inches) or Metric systems. This will update all unit-related fields in all dialogues, as well as the scene's representation.

Unit Factor:
    This value adjusts the relative size of the units without changing the scene geometry.  If, for example, you wanted a box that was 1m square to represent a box that was 2m square, you would change this value from 1 to .5, and then all fields would show that the box was now 2m square.

View Rotation Center:
    This allows you to choose which point the camera will rotate around when you rotate the view.  If Manipulator is chosen, the camera will always rotate around the manipulator or the place where the manipulator last was.  If Framed Selection is chosen, the camera will rotate around the center of the grid until a call to Frame Selection is made, at which point it will begin to rotate around the place where the manipulator was when this call was made.  Rotation will continue to be around this point until the next call to Frame Selection is made.

Persistent Selection:
    This setting, when checked, makes it so that Silo will not deselect your current selection unless you explicitly perform the deselection using the Deselect command or Ctrl+Shift or Alt+Shift dragging with the mouse.

Tesselate Quads (slower):
    This is an option relating to the way Silo displays geometry. When this option is deselected, a quad (4-sided polygon) which is concave may not be displayed correctly. When the option is checked, the program performs extra calculations to better display such polygons. Note that this does not affect the actual geometry of scene objects or the way they are edited, it merely affects the way geometry is displayed.

Texture Size:
    This field allows you to change the resolution at which Silo displays texture images while you're working. Higher resolutions will look closer to the original image, but also consume more memory and may cause the program to run slower.

Mouse Pick Area:
    This setting adjusts the sensitivity of the mouse in selecting the manipulator and geometry on screen.  The number represents the size in pixels of a box centered around the mouse which will act as the picking area.  Thus, larger numbers mean the mouse is less sensitive and will have a larger hit area.

Undo Level:
    This field allows you to set how many operations Silo will keep in memory in order to undo. A larger number of undos will allow you to undo more operations in a row, but will also take up more memory.

Max SubD Level:
    This field allows you to set the maximum number of levels which you can subdivide an object. Each subdivision level becomes increasingly more memory-dependent, so an upper limit is advisable. This limit represents the maximum difference between a control mesh and its underlying refined mesh. If a control mesh is refined using the Refine Control Mesh (Subdivision > Refine Control Mesh) command, its number of available subdivisions is reset to this number.