Calculation Specification¶
This is a template. Replace every bracketed placeholder. This file itself establishes no policy and defines no real calculation until filled in.
Calculations must be specified implementation-agnostically first. Write the business rule in plain language before, and independent of, any Excel formula. The Excel Implementation Note is a secondary, non-authoritative aid — if it and the Business Rule ever disagree, the Business Rule governs and the implementation note must be corrected.
Calculation Template¶
Calculation: [Calculation Name]¶
- Calculation ID: [CALC-ID]
- Name: [Calculation Name]
- Business Purpose: [Why this calculation exists — what customer question it answers]
- Inputs: [List Field IDs from data-dictionary.md and/or other Calc IDs]
- Business Rule: [Plain-language statement of the calculation logic, expressed as if explaining it to a non-technical stakeholder. No formula syntax here.]
- Order of Operations: [If the rule has multiple steps, number them explicitly]
- Units: [Units of inputs and output, and any conversion involved]
- Rounding: [Rounding rule — e.g. round to nearest cent, round half up, no rounding until final display]
- Null Handling: [What happens when a required input is blank/missing]
- Zero Handling: [What happens when an input is legitimately zero, vs. missing]
- Error Handling: [What happens on invalid input — e.g. negative value where only positive is valid — and what the user sees]
- Boundary Conditions: [Edge cases — minimum/maximum plausible values, date boundaries, division-by-zero conditions]
- Output: [Field ID or description of the resulting value, including data type and format]
- Dependencies: [Other Calc IDs or tabs this calculation depends on or feeds]
- Worked Example: [A fully worked numeric example: given inputs X, Y, Z, the result is W, shown step by step]
- Excel Implementation Note: [Non-authoritative note on how this might be implemented in Excel — e.g. which function family, whether an array formula or helper column is anticipated. Not binding; the Business Rule governs.]
- Test Cases: [Reference to test-plan.md test IDs covering this calculation, or list inline: normal case, zero case, null case, boundary case, error case]
Calculation: [Second Calculation Name]¶
[Repeat the structure above for each calculation. Do not combine multiple calculations into one entry.]
This is a template. Replace bracketed placeholders. This file itself establishes no policy.