This holds the single-bit DEI value (0 or 1) this rule matches against, meaningful only when cienaCesAclRuleMatchOuterDei is set true, since the DEI bit is otherwise not part of this rule's match criteria at all. An admin sets this to 1 specifically to target frames already marked drop-eligible by upstream equipment, or to 0 to target frames explicitly marked as not drop-eligible, depending on which population of traffic they want this rule to affect. For example, a rule matching cienaCesAclRuleOuterDei=1 combined with a permit action might be used to specifically allow drop-eligible traffic through a congested link while a separate rule handles non-drop-eligible traffic differently.