Meaning of CI in English
Congestion Indicator: This is a field in a RM-cell, and is used to cause the source to decrease its ACR. The source sets CI=0 when it sends an RM-cell. Setting CI=1 is typically how destinations indicate that EFCI has been received on a previous data cell.
ATM Forum English vocabulary. Английский словарь организации Форум ATM. 2012