Foundations

Reflection angles are measured from the local normal.

Total reflected flux does not mean zero field beyond the interface.

A virtual image is formed by ray extensions, not actual ray convergence.

Photon frequency sets maximum photoelectron energy in the single-photon model.

A momentum state has a spatial wave phase.

Equal dimensions do not make quantities interchangeable.

A numerical value depends on the chosen unit.

Coherence means no extra numerical factor in the base-unit product.

Ordering and category labels do not justify ordinary arithmetic.

A physical phenomenon, an approach and a detailed procedure have different roles.

A complete measurement system can include more than one device.

Component names describe different measurement roles.

A displayed reading is only one part of a measurement result.

Changing an instrument response differs from determining its calibration.

An accepted comparison value need not be an exact true value.

Possible readings differ from a validated interval of measurement.

Instrument properties are specified within a domain of use.

Responding to a target differs from excluding interference.

An undetected input change differs from an interval with no output change.

Time stability differs from short-term repeatability.

A specification limit is not an uncertainty estimate.

More repetitions do not resolve an underspecified measurand.

Relative uncertainty uses a nonzero measured magnitude.

A zero or blank reading can still have uncertainty.

An intended-use target differs from achieved uncertainty.

Within-location changed conditions differ from strict repeatability.

Certification alone does not establish equivalence across procedures.

Chemical composition and spatial uniformity describe different features of matter.

A change of phase need not change chemical identity.

A formula's subscripts represent different information in different chemical models.