The S command replaces occurrences of one string of characters with
 another.

 Format: [+|-][count]S/string-1/string-2/

 The slashes represent any non-alphanumeric character used to delimit the
 two strings.  S searches in the specified direction from the cursor and
 finds an occurrence of string-1.  It deletes string-1 and inserts
 string-2 in its place.

 Ex: S/1988/1989/