C1 OK - the starting classification N0 is present.
C2 OK - the first expansion produced N1 together with side labels I1 and J1.
C3 OK - the chain reaches the midpoint N5000 and still carries both side-label branches.
C4 OK - the final taxonomy step from N9999 to N10000 was completed.
C5 OK - once N10000 is reached, the terminal class A2 is derived.
C6 OK - the success flag is raised only after the terminal class A2 is present.