semantics are perl5.  version is 0.207.4.  start symbol is S.

S: A, Z. q{ $_->[0] . ", but " . $_->[1] }. # Call me the start rule
note: you can also call me Rule 0.

A: . q{'A is missing'}. # Call me Rule 1

A: B, C. q{"I'm sometimes null and sometimes not"}. # Call me Rule 2

B: . q{'B is missing'}. # Call me Rule 3

C: . q{'C is missing'}. # Call me Rule 4

C: Z.  q{'C matches Z'}. # Call me Rule 5

Z: /Z/. q{'Zorro was here'}. # Call me Rule 6