CellEpilog is an option for Cell which gives an expression to evaluate after each ordinary evaluation of the contents of the cell.
CellOpen is an option for Cell that specifies whether the contents of a cell should be explicitly displayed.
CellProlog is an option to Cell that gives an expression to evaluate before each ordinary evaluation of the contents of the cell.
Collect
(Built-in Mathematica Symbol) Collect[expr, x] collects together terms involving the same powers of objects matching x. Collect[expr, {x_1, x_2, ...}] collects together terms that involve the same powers ...
CopyFile["file_1", "file_2"] copies file_1 to file_2.
DefaultDuplicateCellStyle is a notebook option that specifies the default style to use for cells created by automatic duplication of other cells in the notebook.
DefaultFieldHintStyle is a low-level option for InputField that specifies the default style to use for displaying the field hint.
DelimiterMatching is an option for selections that specifies whether an opening delimiter will match only its respective closing delimiter or any closing delimiter.
Element
(Built-in Mathematica Symbol) Element[x, dom] or x \[Element] dom asserts that x is an element of the domain dom. Element[{x_1, x_2, ...}, dom] asserts that all the x_i are elements of dom. Element[patt, ...
EndDialogPacket[integer] is a MathLink packet indicating the end of the Dialog subsession referenced by integer.