IEC PAS 63228:2020(E) This Book 12 defines LED Arrays with a rectangular shape and a circular light emitting surface. For each LED Array, this Book 12 also defines the mechanical interface between the LED Array and the corresponding Holder. The mechanical interface between the Holder and the Luminaire (e.g. outline, OCA and mounting holes) is defined in [Book-10]. This Book 1 defines the common concepts that underlie the Zhaga interface specifications. In addition, this Book 1 specifies general requirements for Zhaga compliant components of LED Luminaires.