Ntlha e e Kwa Tlase

a ISO ke khutshwafatso ya International Standards Organization; ASA, ke khutshwafatso ya American Standards Association. Mo dikarolong tse dingwe tsa Yuropa, gape go dirisiwa DIN (Deutsche Industrie Norm). Filime e e kwadilweng ISO 100/21 ke ASA 100, kana 21 DIN.