Booleans represents the domain of Booleans, as in x \[Element] Booleans.
DMSList
(Built-in Mathematica Symbol) DMSList[\[Theta]] converts an angle \[Theta] given in decimal degrees to a DMS list {degree, minute, second}.DMSList["dms"] converts a DMS string to a DMS list {degree, ...
FractionBox[x, y] is a low-level formatting construct that represents x/y in notebook expressions.
Khinchin is Khinchin's constant, with numerical value \[TildeEqual] 2.68545.
MenuStyle is an option for menu-generating constructs that specifies the style to use in displaying menu items.
StringQ
(Built-in Mathematica Symbol) StringQ[expr] gives True if expr is a string, and False otherwise.
WindowTitle is an option that specifies the title to give for a window.
All textual and graphical forms in Mathematica are ultimately represented in terms of nested collections of boxes. Typically the elements of these boxes correspond to objects ...
Expressions corresponding to cells. Here is a notebook containing a text cell and a Mathematica input cell. Here are the expressions corresponding to these cells.
PieChart[{y_1, y_2, ...}] makes a pie chart with sector angle proportional to y_1, y_2, ....PieChart[{..., w_i[y_i, ...], ..., w_j[y_j, ...], ...}] makes a pie chart with ...