[plt-scheme] grammar for regexps

A small confusion about the grammar for regexps (Ch. 10 of PLT 
MzScheme: Language Manual). It reads that the two productions for the 
Pieces non-terminal are:

     Pieces ::= Piece
             |  PiecePiece

This means there can be exactly one or exactly two pieces. Was this 
supposed to be:

     Pieces ::= Piece
             |  PiecePieces

i.e., a non-empty list of Piece elements? Either I'm missing something 
obvious (quite possible), or this would mean you could only ever match 
(within a particular alternate) a string of either one or two 
characters.

Thanks,
Dave