Decision tables

Turn the rules with several conditions into tables that show an outcome for every combination, so that gaps and overlaps show before anyone builds anything.

When three or more conditions decide one outcome. Inputs: the rules register. Feeds: requirements, stories, the BRD, tests and the review exercise.

• List the conditions as yes-or-no questions, and cite the rule behind each.
• List the actions, one per row.
• Fill the rules column by column, with "-" where a condition does not matter and X for each action the rule takes.
• Check completeness with the formula row, then read any two rules that differ in one entry only.
• Write down the order in which the tables are applied, if it matters.

1. Is every combination covered? Answered in The completeness row under each table: 8 of 8 for DT-01, 32 of 32 for DT-02, DT-03 and DT-04.
2. Do any two rules overlap? Answered in Every table: each pair of rules has at least one condition where one says Y and the other N, so no two overlap.
3. In what order are the tables applied? Answered in Tables sheet, column Order. DT-03 comes before DT-04, because the cost limit is applied before any exemption (BR-37).
4. Where does each outcome come from? Answered in The Rules applied row under each table, and the rule cited in each condition and action.
5. Which rules has a test case proved? Answered in The Tested by row under each table, filled from document 18.

• Missing combinations. You can spot them when the completeness row shows Gap.
• Conditions that are not yes-or-no: a condition with three answers is a second table in disguise.
• Actions mixed in with conditions: an action that contains "if" hides a condition from the completeness check.
• An order of evaluation that is assumed but not written: two tables could both apply to the same case, and nobody says which goes first.
• One table doing four jobs: it has more than five conditions, or rules that never share an action.

• The routine check comes before the environmental one in DT-01. The regulator's own example of an enquiry made in the normal course of business is a question about refuse collection dates GUIDE SRC-06. Rejected: asking about environmental information first, which would send every routine question about waste or noise into the EIR, against the regulator's reading.
• No action in DT-02 hides a condition. Contact details are asked for in a rule of their own, R2, and the note on Table 2 says why an EIR part that is too general meets R3 first. R5 only advises a person who asked orally to write. Noting the request for someone who cannot write is BR-14 and REQ-05, and the verified note comes back to the table as a written request. Rejected: "if there is no address, ask for one" or "note it if a disability prevents writing" written into an action, which the completeness check cannot see.
• DT-03 comes before DT-04 for FOIA parts, and only its "go on" rules reach DT-04 (BR-37). Rejected: one table for cost and exemptions, which would need ten conditions and 1,024 combinations.
• In DT-04 a tie in the public interest test counts as No. Both regimes withhold only when the public interest in withholding "outweighs" the public interest in disclosure LAW SRC-01 s.2(2), SRC-03 reg. 12(1). The EIR also add a presumption in favour of disclosure LAW SRC-03 reg. 12(2). Rejected: leaving the tie undefined, which is a gap the completeness check cannot find.