Number
(Built-in Mathematica Symbol) Number represents an exact integer or an approximate real number in Read.
OverHat
(Built-in Mathematica Symbol) OverHat[expr] displays with a hat over expr.
OverscriptBox[x, y] is the low-level box representation for OverscriptBox[x, y] in notebook expressions.
OverscriptBoxOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option that specifies the style and display of OverscriptBox constructs.
OverTilde[expr] displays with a tilde over expr.
OverVector[expr] displays with a right vector over expr.
PalettePath is a global option that specifies which directories Mathematica searches for palettes on startup.
ParagraphSpacing is an option for Cell, StyleBox, and Style that specifies how much extra space to leave between successive paragraphs of text.
Properties is an option that allows specification of properties to objects and items of objects.
QuotientRemainder[m, n] gives a list of the quotient and remainder from division of m by n.