Guidelines for defining an implicit unordered group that has no delimiter

  • The type of a component cannot be a binary item whose length is not fixed.
  • The type of a component must be content-distinguishable from the type of each other component.
  • If the type of a component is unbound, the type must be
    ending-distinguishable from the type of each other component.
  • If the maximum range is greater than one and the type is unbound, the type must be ending-distinguishable from itself.