# Declare inputs and exact calculations

Set meaningful types, bounds, precision and expressions before checking boundary cases.

Source: https://help.smartfact.ai/manuals/factoryspec/inputs-and-calculations

Review edition: 25 October 2026

Roles: author, reviewer

Inputs and calculations state how the engineering source is represented. Define them before adding comfortable passing cases. A wrong unit, step or applicability condition can make a plausible result misleading even when the formula itself appears familiar.

## Declare each input

In Inputs, enter Input key and Input label. Choose Input type and Measurement / purpose. Set Minimum, Maximum and Exact step where applicable. Length controls identify millimetres. Decimal places and allowed option keys form part of the accepted grammar and engineering meaning.

Use Applies when for an input that belongs only to certain configurations. Check both applicable and inapplicable cases. Do not make an essential input optional merely because the current source record is incomplete. Ask for the missing source fact or block the unsupported configuration.

Keep keys stable and distinct. The label helps the person entering dimensions; the key identifies the value expressions and case facts use. A more readable label should not accidentally point a calculation at another quantity.

## Define each calculation

In Calculations, supply a key, label and result type. Set decimal precision when relevant and build the expression from declared values. Check that a length result represents a length and a count represents the intended number per configured unit.

Review rounding, exact steps and boundary behaviour against the engineering source. A quantity calculated for one unit is not automatically the total for an order. Keep any source references with the family so the reviewer can reproduce the intended arithmetic independently.

## Prove meaning with cases

Supply independent expected named values for ordinary dimensions, allowed extremes and step boundaries. Include invalid or blocked configurations where the source requires refusal. A proof mismatch can mean either the model or the expectation is wrong, so inspect both against the engineering source rather than copying actual output into expected fields.

Use Save draft and read the stored proof before submission. Follow [Write independent cases](/manuals/factoryspec/independent-cases) and [Review a candidate](/manuals/factoryspec/candidate-review) for the checks that make these declarations reviewable.