DialogInput[expr] interactively puts up expr as a dialog notebook, waits until a DialogReturn[e] is evaluated from within it, and then returns the result e. DialogInput[{x = ...

Except[c] is a pattern object which represents any expression except one that matches c. Except[c, p] represents any expression that matches p but not c.

False is the symbol for the Boolean value false.

FractionBox[x, y] is a low-level formatting construct that represents x/y in notebook expressions.

FractionBoxOptions -> {opt_1 -> val_1, opt_2 -> val_2, ...} is an option for cells that specifies settings for FractionBox objects within the cell.

Front is a symbol that represents the front of a graphic for purposes of placement and alignment.

IncludeConstantBasis is an option for LinearModelFit and other fitting functions that specifies whether a constant term should be included if not explicitly given in the list ...

IntegerString[n] gives a string consisting of the decimal digits in the integer n. IntegerString[n, b] gives a string consisting of the base b digits in the integer n. ...

LinkLaunch["prog"] starts the external program prog and opens a MathLink connection to it.

Manual represents an option or other value that is to be selected manually, usually by some form of interactive manipulation.