This part of ISO 23552 specifies safety, construction and performance requirements for electronic fuel/air ratio control systems intended for use with gas or oil burners and gas or oil burning appliances. It also describes the test procedures for evaluating these requirements and specifies information necessary for installation and use. This part of ISO 23552 is applicable only to closed-loop fuel/air ratio controls (see 3.1) and does not differentiate into classes by heat input. This part of ISO 23552 applies to electronic fuel/air ratio control systems that can be tested independently or as part of an appliance or as part of a burner.