this paper aims to contribute to the precision of legislative language. Through the analysis of a number of central legal concepts and a discussion of the mutual relations between these concepts, it aims to provide legislators with conceptual tools that facilitate precise legislative drafting. The present paper is the first of a projected series of four papers and deals with rules and in particular with a subset of them, norms. The other three projected papers are to deal with legal positions, including rights, with juridical acts such as contracts, legislation and administrative dispositions, and with the ‘logic’ of rules, such as rule conflicts, the relation between rules, principles, rights, and values, exceptions to rules, and analogous...