argument `required-features'.
        (insert-char-attributes): For each character in relation features
        [->FOO or <-FOO] and `ideographic-structure', specify
-       required-features pf `char-db-insert-char-spec' based on *sources.
+       required-features of `char-db-insert-char-spec' based on *sources.
 
        * Ideograph-R057-Bow.el, Ideograph-R056-Shoot.el,
        Ideograph-R055-Two-Hands.el, Ideograph-R049-Oneself.el,