-- The child @child is used as a local variable,
-- which is not allowed because its type is a Nonterminal
-- You should use @child.self in this situation.

DATA Noot
  | One
  | Two
  
DATA Aap 
	| Een child : Noot
	
ATTR Aap [ | | synth : Noot ]

SEM Aap
  | Een   lhs.synth = @child