An ATM cell, as defined by the PTI, cannot be:

A.
User data cell

B.
Idle cell

C.
OAM segment flow cell

D.
OAM segment flow cell

E.
RM cell

F.
OAM end-to-end flow cell

G.
AAL2 cell

Explanation:
A 3-bit Payload Type Indicator (PTI) field indicates the type of data being carried in the payload. The high-order bit is a “0” if the payload contains user information and is a “1” if it carries connection management information. The second bit indicates if the cell experienced congestion over a path. If the payload is user information, the third bit indicates if the information is from Customer Premises Equipment. The PTI field is identical for UNI/NNI/STI.