NOT.7:4.1 - Locate the operation and its failure

Select a concrete question and the expression on which the reader must work. Ask for the answer or modification, not only an opinion of the notation. Recover the route taken: where the reader searches, which reference is followed, what has to be held in memory and where the result goes wrong or the work becomes costly.

Use an available response or observed difficulty when one exists. Otherwise, walk through the operation and treat the diagnosis as a design estimate. An actual trial is useful when plausible reader responses would change the repair decision; it is not a prerequisite for every obvious correction.

State the relevant preparation, permitted help, display or access conditions and effort limit. A reader who knows the local grouping convention faces a different question from one learning it. A page that hides half a diagram can create a different difficulty from the diagram’s structure.

Keep the intended result in view. If the reader has correctly recovered the notation but lacks the subject inference, obtain that inference or capability. If an interpretation is ambiguous, NOT.2 or NOT.3 repairs the rule before comparisons of ease can settle its use.