ISO 9186-1:2007 specifies methods for testing the comprehensibility of graphical symbols. It includes the method to be used in testing the extent to which a variant of a graphical symbol communicates its intended message and the method to be used in testing which variant of a graphical symbol is judged the most comprehensible.The purpose of ISO 9186-1:2007 is to ensure that graphical symbols, and signs using graphical symbols, are readily understood. The intention is to develop graphical symbols which are correctly understood by users when no supplementary (i.e. explanatory) text is presented. When such a graphical symbol cannot be obtained, it might be necessary to present a graphical symbol together with supplementary text explaining its meaning in the language of the intended users.