title: what does | mean when there is no right side in antlr
body: <p>I saw this in a antlr grammar today but am not sure what it means.  I wish google would let me search for characters...</p>
  
  <p>resultList: (STAR | attributeList |) -> ^(RESULT attributeList? STAR?);</p>
  
  <p>Notice the second "|" character has no right side element?  What does that mean?</p>
  
  <p>thanks,
  Dean</p>