This part of IEC 61249 gives requirements for properties of non-halogenated epoxide woven Eglass reinforced laminated sheets of defined flammability (vertical burning test), copper-clad in thicknesses 0,05 mm up to 3,2 mm. The flammability rating is achieved through the use of non-halogenated inorganic and/or organic compounds acting as fire retardants. These fire retardants are contained as part of the polymeric structure or in addition to it. The glass transition temperature is defined to be 120 °C minimum. Some property requirements may have several classes of performance. The class desired must be specified on the purchase order, otherwise the default class of material may be supplied.