Discussion: Non standard or conventional symbols sometimes defeat the purpose of developing a standard modeling language that can improve the consistency, usability, and reusability of the model. Different analysts may opt to use different symbols and notations to convey the same meaning. This situation creates inconsistency in reading and interpreting the model. This does not imply, however, that expanding i* notation using non-standard syntax is not allowed. New notations might add expressive power. The requirements are that the new notation needs to be clearly explained and the existing i* notation cannot be used instead.