Semantic Typography

Date Formats

Date order, separators, month names, and abbreviations are locale- and purpose-dependent; ambiguous numeric dates require human interpretation.

Reviewed 2026-08-20Locale-dependent conventionContext required
CategorySemantic Typography
Rule strengthLocale-dependent convention
Locale applicabilityall
Avellio detectionSupported
Issue identifiersDATE_FORMAT
Correction authorityPreview/manual only; ambiguous date order is never automatically converted.

Definition

The same numeric string can name different dates in different regions. Prose, tables, filenames, and data exchange also have different requirements; ISO-style ordering can be appropriate for machine-readable or international contexts.

BAD vs GOOD

BAD
Ambiguous

03/04/2026

GOOD
Explicit

3 April 2026 (UK context) or April 3, 2026 (US context)

Why it matters

An incorrect date conversion can change meaning, not merely appearance.

Rule strength

Locale-dependent convention. This is not an absolute linguistic law; locale, genre, content, and house style can change the correct decision.

Exceptions and editorial considerations

  • Machine-readable data may require ISO 8601 regardless of prose locale.
  • Legal, archival, and institutional styles can impose their own format.

How to fix it manually

  1. Determine the intended date before changing characters.
  2. Select a publication-wide or context-specific format.
  3. Use month names where ambiguity would matter.
  4. Check tables and running text separately.

Adobe InDesign guidance

Find/Change can normalize a proven pattern but should not infer ambiguous day/month order. Review imported data at its source where possible.

How Avellio detects it

Avellio emits DATE_FORMAT for mixed or locale-inconsistent recognized date patterns and reports concrete unambiguous regional conflicts.

Action safety

Preview/manual only; ambiguous date order is never automatically converted.

Check this automatically in Adobe InDesign

Language and locale differences

EN US

Month–day–year is expected when the order is unambiguous.

EN UKEN AUEN NZFRDEESPTBRIT

Day–month–year is common, with locale-specific separators and month treatment.

HU

Year–month–day is the profile model.

Compare all published language and locale guides.

Authoritative references

  1. Avellio User Manual — Locale profile referenceAvellio product source
  2. Unicode CLDR — Date and time patternsLocale data standard
  3. GOV.UK content and publishing guidance — A to Z style guideEditorial style guide

Avellio references document product behavior. External standards and authorities support the general or locale-specific typographic guidance. Where traditions disagree, this page states the disagreement instead of manufacturing one universal rule.