oi -- Option Indent

                default range           syntax
                    1, $                  oi[a | <indent>]

        "oi" selects the indent value for lines  inserted with "a" and
        "i" commands (initially 1). "a" selects auto-indent which sets
        the indent to the value  which equals the indent of the previ-
        ous line.  If  neither  "a" nor  "<indent>" is  specified, the
        current value of indent is displayed.

        For general information about the option command, type "ho".