AutoIndent is an option for Cell which specifies what automatic indentation should be done at the beginning of a new line after an explicit return character has been entered.
Possible settings for AutoIndent are:
With AutoIndent->True, tabs or spaces used for indentation on the previous line are explicitly inserted at the beginning of the new line.
With AutoIndent->Automatic, line breaks are always indicated by an IndentingNewLine character even if they were originally entered using or \[NewLine].
Indentation after an \[IndentingNewLine] is automatically redone every time an expression is displayed.
The amount of indentation after an IndentingNewLine is determined by the settings for the LineIndent and LineIndentMaxFraction options.
See Section 2.11.11.
See also: LineIndent, ParagraphIndent, ShowAutoStyles.
New in Version 3; modified in 4.0.