Although, in t' strictest sense, Amateur Rocketry encompasses all hobby rocketry, ya bilge rat, t' phrase is usually used for activites outside t' scope o' low t' high-power rocketry as defined by t' model rocket and high-power safety codes as defined by t' National Association o' Rocketry and t' Tripoli Rocketry Association. These activities often include t' manufacture and use o' types o' propellants which may be very hazardous.