This is the destination-port analog of cienaCesAclRuleMatchL4SrcPort, indicating whether this rule matches any destination port, a single specific one, or a bounded range -- notably the MIB's own description text for the 'single' case appears to reference the source-port field by name rather than the destination field, which reads as a copy-paste inconsistency in the vendor's source documentation rather than an intentional cross-reference. An admin should treat this as governing the destination-side fields (cienaCesAclRuleL4DstPort and cienaCesAclRuleL4DstPortUpper) despite that apparent documentation slip, since the object naming and table structure make clear this is the destination-port match-type control. For example, an admin blocking access to a specific destination service would set this to single and configure cienaCesAclRuleL4DstPort with that service's port number, such as 3389 for RDP.