Chapter 5. Place References–Switches

Place references refer to positions of program statements, and the simplest position market if the label (see ). A switch is a preset and unalterable array of labels, which must be within scope at the switch declaration. Any use of the indexed switch name refers to the corresponding label. For example, the switch declaration


SWITCH s := a, b, c

causes s[1] to refer to the label a, s[2] to b and s[3] to c. The syntax rules are


      Switchdec ::= 
    SWITCH
      Switch := Labellist
    


      Labellist ::= 
    Label
      Label , Labellist
    


      Switch ::= Id
    


      Label ::= Id