title: JPA: @OrderColumn and visible state of an entity?
body: <p>This is a followup question to:</p>
  
  <p><a href="https://stackoverflow.com/questions/9957247/is-manytomanymappedby-ordercolumn-supported-by-the-jpa">Is @ManyToMany(mappedBy = ... ) + @OrderColumn supported by the JPA?</a></p>
  
  <p>I'm referring to the <code>@OrderColumn</code> Java docs:</p>
  
  <p><a href="http://docs.oracle.com/javaee/6/api/javax/persistence/OrderColumn.html" rel="nofollow noreferrer">http://docs.oracle.com/javaee/6/api/javax/persistence/OrderColumn.html</a></p>
  
  <p>The text there is the same as what the JPA 2 spec writes in section <em>11.1.39 OrderColumn Annotation</em>.</p>
  
  <p>What does the part "the order column is not visible as part of the state of the entity" mean <strong>exactly</strong>? There's a lot of room for interpretation on that.</p>
  
  <p>Does that mean the order column must not be part of any FKs and/or PKs defined? Or only not in FKs (PK allowed)? What does the state of an entity comprise? AFAIK the JPA spec doesn't define that.</p>
  
  <p>Thanks</p>