Physical dimensions
ISO A-series trim dimensions are based on ISO 216:2007. North American and photo dimensions are stored in their native inches and converted using the NIST-defined exact relationship of 25.4 millimetres per inch.
Resolution terminology
Adobe Photoshop documentation is used as a reference for pixel dimensions, PPI, physical print size and resampling concepts. Printer-specific bleed and resolution requirements always take precedence over generic guidance.
Verification policy
Calculation rules, standard presets, unit conversions, rounding boundaries and invalid-input behavior are covered by deterministic tests. Source-dependent guidance is dated and should be rechecked when documentation or industry practice changes.