This attribute specifies delay acknowledgment timer mechanism.
If this attribute is set to no, then the Vc will automatically return
acknowledgment packets without delay. If this attribute is set to yes,
then the Vc will wait for one second in an attempt to piggyback the
acknowledgment packet on another credit or data packet. If the Vc
cannot piggyback the acknowledgment packet within this time, then
the packet is returned without piggybacking.