This part of IEC 61249 gives requirements for properties of modified non-halogenated epoxide woven E-glass laminated sheet 0,05 mm up to 3,2 mm, of defined flammability (vertical burning test), copper-clad. The flammability rating is achieved through the use of phosphorus compounds and/or aluminium hydroxide fire retardants contained as part of the polymeric structure. The glass transition temperature is defined to be between 150 °C to 190 °C. Some property requirements may have several classes of performance. The class desired should be specified on the purchase order, otherwise the default class of material will be supplied.