This attribute is applicable and is displayed only for connections for
which the operational Tm abrConnectionType is displayed as
sourceDest or virtualSourceDest.
This attribute indicates the Transient Buffer Exposure (TBE) for
this connection. TBE is the negotiated number of cells that the
network would like to limit the resource to send during start-up
periods, before the first Resource Management (RM) cell returns.
For nailed-up connections, this attribute is determined by the
provisioned value of the transientBufferExposure attribute. For
signalled connections, it is indicated in the ABR Setup Parameters
Information Element.