Diagnosis
This node combination is not permitted here.

Procedure
Combination rules for the second hierarchy level:
- All features are allowed just one node if the node is of the
decision operation or subfeature access type.
- A main feature is also allowed just one node if the node is of
the program access type. Furthermore, a main feature with field
return is allowed just one node if the node is of the return
value type.
- The error operation, root, and field value node types are not
permitted here.
- Two nodes are allowed if one of them contains a debugging
operation.
- A main feature with table return is allowed a maximum of 36
nodes if all of the nodes contain return lines, or a maximum
of 35 return lines and just one debugging operation.
- A subfeature is allowed a maximum of 36 nodes if all of the nodes
contain return lines or program accesses, or 35 and just one
debugging operation.
Combination rules for field value nodes:
- The field value node must have a node child.
- The node child must not be of the field value type.
- The field value node can have just one node child if the node
child is of the decision operation, error operation, or subfeature
access type.
- A field value node for a main feature can also have just one node
child if the node child is of the program access type. Furthermore,
a field value node for a main feature with field return can also
have just one node child if the node child is of the return value
type.
- Two node children are also allowed if one node child is a
debugging operation.
- If a main feature has table return, a maximum of 36 node children
are allowed if all of the node children contain return lines, or a
maximum of 35 return lines and just one debugging operation.
- A subfeature is allowed a maximum of 36 node children if they all
contain return lines or program accesses, or 35 and just one
debugging operation.