A security control for an information system that has not been designated as a common control or the portion of a hybrid control that is to be implemented within an informational system is referred to

A logical control is a type of security control (e.g., software, policies) but not a classification based on its scope of application (common, system-specific, hybrid).

A system-specific control is precisely defined as a security control that is not a common control and is implemented within and inherited by a single information system, or the part of a hybrid control specifically implemented by the information system. These controls address risks unique to that particular system.

A common control is designed to be inherited by multiple information systems, which directly contradicts the question's premise that it 'has not been designated as a common control'.

A hybrid control is a combination of common and system-specific controls, but the question specifically describes the system-specific portion or a control not common.