NOT.Preface:3.1 - Design what can be expressed and done

NOT.1 derives a design requirement from the operation and from cases that need different treatment. NOT.2 constructs formation, grouping, scope and reference rules. NOT.3 gives the resulting expressions a meaning and a route by which a prepared reader obtains a consequence. These contributions connect what the work needs, what can be written and what the reader can do with it.

NOT.4 constructs changes to expressions, with their applicability conditions and preserved observations. A mathematical argument may justify a rewrite. A computational procedure may apply it. A surrounding physical or organizational use determines whether the preserved observation is sufficient. The same marks can therefore admit one transformation in a pure calculation and require another treatment when each occurrence performs an interaction.