This field lets a rule match by a named, higher-level Layer-4 destination protocol/application (rather than a bare numeric port), and the description flags an important mutual-exclusivity constraint: this field and cienaCesAclRuleMatchL4DstPort cannot both be set to something other than 'any' on the same rule at the same time. An admin must therefore choose one matching approach per rule -- either match by a specific named protocol/application or by a specific destination port/range -- but not attempt to combine both criteria in a single rule row. For example, an admin wanting to match a protocol by name via this field rather than manually specifying its destination port through the other field would need to leave cienaCesAclRuleMatchL4DstPort at its 'any' default to respect this exclusivity rule.