CellLabelPositioning is an option for cells that specifies where the label for a cell is positioned.
CellOpen is an option for Cell that specifies whether the contents of a cell should be explicitly displayed.
ClearSystemCache[] clears internal system caches of stored results.
CreateScheduledTask[expr] creates a task that will repeatedly evaluate expr once per second.CreateScheduledTask[expr, time] creates a task that will repeatedly evaluate expr ...
Darker
(Built-in Mathematica Symbol) Darker[color] represents a darker version of the specified color. Darker[color, f] represents a version of the specified color darkened by a fraction f. Darker[image, ...] ...
DefaultNaturalLanguage is an option for character selections that specifies the language used when checking the spelling of a word in a human natural language selection.
Deletable is an option for Cell that specifies whether the cell can be deleted interactively using the front end.
DeleteDirectory["dir"] deletes the specified directory.
DeleteFile["file"] deletes a file. DeleteFile[{"file_1", "file_2", ...}] deletes a list of files.
DelimiterMatching is an option for selections that specifies whether an opening delimiter will match only its respective closing delimiter or any closing delimiter.