ScriptLevel is an option for selections that is used in determining the font size of modifiers such as subscripts and superscripts in a nested expression.
ScriptMinSize is an option for Style that specifies the minimum font size to use in rendering subscripts, etc.
Setting
(Built-in Mathematica Symbol) Setting[expr] replaces control objects such as sliders or popup menus in expr by their settings.
ShowCellBracket is an option for Cell that specifies whether to display the bracket that indicates the extent of the cell.
ShowClosedCellArea is an option for cells that specifies whether a rectangular bar is displayed next to a closed cell group to indicate the number of cells in the group.
ShowContents is an option for selections that specifies whether an object represented by a StyleBox should be displayed on the screen or replaced by blank space.
ShowSpecialCharacters is an option for Style and Cell that specifies whether to replace \[Name], \:nnnn, etc. by explicit special characters.
SingleLetterItalics is an option for Cell that specifies whether single-letter names should be displayed in italics.
Small
(Built-in Mathematica Symbol) Small is a style or option setting that specifies that objects should be small.
SpanAdjustments is an option for selections that specifies the height and width of spanning characters.