function Extend_Node (Node : Node_Id) return Entity_Id;
-- This function returns a copy of its input node with an extension
-- added. The fields of the extension are set to Empty. Due to the way
- -- extensions are handled (as two consecutive array elements), it may
+ -- extensions are handled (as four consecutive array elements), it may
-- be necessary to reallocate the node, so that the returned value is
-- not the same as the input value, but where possible the returned
-- value will be the same as the input value (i.e. the extension will