In Enriched mode, you can specify different amounts of indentation for the right or left margin of a paragraph or a part of a paragraph. These margins also affect fill commands such as M-q (see Filling Text).
The Indentation submenu of Text Properties offers commands for specifying indentation:
Indent the region by 4 columns (
Enriched mode, this command is also available on C-x TAB; if
you supply a numeric argument, that says how many columns to add to the
margin (a negative argument reduces the number of columns).
Remove 4 columns of indentation from the region.
Indent Right More
Make the text narrower by indenting 4 columns at the right margin.
Indent Right Less
Remove 4 columns of indentation from the right margin.
standard-indent specifies how many columns these
commands should add to or subtract from the indentation. The default
value is 4. The default right margin for Enriched mode is controlled
by the variable
fill-column, as usual.
You can also type C-c [ (
set-left-margin) and C-c
set-right-margin) to set the left and right margins. You
can specify the margin width with a numeric argument; otherwise these
commands prompt for a value via the minibuffer.
The fill prefix, if any, works in addition to the specified paragraph indentation: C-x . does not include the specified indentation’s whitespace in the new value for the fill prefix, and the fill commands look for the fill prefix after the indentation on each line. See The Fill Prefix.