Option settings for diff mode. It can consist of the following items. All are optional. Items must be separated by a comma.

    filler          Show filler lines, to keep the text
                    synchronized with a window that has inserted
                    lines at the same position.  Mostly useful
                    when windows are side-by-side and 'scrollbind'
                    is set.

    context:**{n}**     Use a context of **{n}** lines between a change
                    and a fold that contains unchanged lines.
                    When omitted a context of six lines is used.
                    When using zero the context is actually one,
                    since folds require a line in between, also
                    for a deleted line.
                    See `fold-diff`.

    iblank          Ignore changes where lines are all blank.  Adds
                    the "-B" flag to the "diff" command if
                    'diffexpr' is empty.  Check the documentation
                    of the "diff" command for what this does
                    exactly.
                    NOTE: the diff windows will get out of sync,
                    because no differences between blank lines are
                    taken into account.

    icase           Ignore changes in case of text.  "a" and "A"
                    are considered the same.  Adds the "-i" flag
                    to the "diff" command if 'diffexpr' is empty.

    iwhite          Ignore changes in amount of white space.  Adds
                    the "-b" flag to the "diff" command if
                    'diffexpr' is empty.  Check the documentation
                    of the "diff" command for what this does
                    exactly.  It should ignore adding trailing
                    white space, but not leading white space.

    iwhiteall       Ignore all white space changes.  Adds
                    the "-w" flag to the "diff" command if
                    'diffexpr' is empty.  Check the documentation
                    of the "diff" command for what this does
                    exactly.

    iwhiteeol       Ignore white space changes at end of line.
                    Adds the "-Z" flag to the "diff" command if
                    'diffexpr' is empty.  Check the documentation
                    of the "diff" command for what this does
                    exactly.

    horizontal      Start diff mode with horizontal splits (unless
                    explicitly specified otherwise).

    vertical        Start diff mode with vertical splits (unless
                    explicitly specified otherwise).

    closeoff        When a window is closed where 'diff' is set
                    and there is only one window remaining in the
                    same tab page with 'diff' set, execute
                    `:diffoff` in that window.  This undoes a
                    `:diffsplit` command.

    hiddenoff       Do not use diff mode for a buffer when it
                    becomes hidden.

    foldcolumn:**{n}**  Set the 'foldcolumn' option to **{n}** when
                    starting diff mode.  Without this 2 is used.

    followwrap      Follow the 'wrap' option and leave as it is.

    internal        Use the internal diff library.  This is
                    ignored when 'diffexpr' is set.
                    When running out of memory when writing a
                    buffer this item will be ignored for diffs
                    involving that buffer.  Set the 'verbose'
                    option to see when this happens.

    indent-heuristic
                    Use the indent heuristic for the internal
                    diff library.

    algorithm:**{text}** Use the specified diff algorithm with the
                    internal diff engine. Currently supported
                    algorithms are:
                    myers      the default algorithm
                    minimal    spend extra time to generate the
                               smallest possible diff
                    patience   patience diff algorithm
                    histogram  histogram diff algorithm

Examples:

:set diffopt=internal,filler,context:4
:set diffopt=
:set diffopt=internal,filler,foldcolumn:3
:set diffopt-=internal  " do NOT use the internal diff parser

(default "internal,filler,closeoff")

not available when compiled without the +diff feature