Breaks & Structure

Non-breaking Spaces

A non-breaking space preserves visible separation while preventing a line break between related items.

Reviewed 2026-08-20Strong structural principle with locale-specific applicationsContext required
CategoryBreaks & Structure
Rule strengthStrong structural principle with locale-specific applications
Locale applicabilityall
Avellio detectionSupported
Issue identifiersPREPOSITIONUNIT_SPACE
Correction authorityGuarded recognized unit pairs can enter Safe Clean; exact Czech/Polish short-word cases require Review Queue.

Definition

Unicode distinguishes ordinary SPACE from NO-BREAK SPACE (U+00A0) and NARROW NO-BREAK SPACE (U+202F). Both visible no-break spaces inhibit breaks, but their width and conventional uses differ.

BAD vs GOOD

BAD
Breakable pair

12 kg

GOOD
Protected pair

12 kg

Why it matters

Keeping a number with its unit, a short word with the following word, or punctuation with its phrase prevents misleading or ugly line endings.

Rule strength

Strong structural principle with locale-specific applications. This is not an absolute linguistic law; locale, genre, content, and house style can change the correct decision.

Exceptions and editorial considerations

  • Not every adjacent pair should be locked; excessive no-break spaces can create poor composition.
  • Some publishers choose NBSP where others choose NNBSP.

How to fix it manually

  1. Insert the intended no-break character, not repeated ordinary spaces.
  2. Choose NBSP or NNBSP according to the publication standard.
  3. Recompose and inspect the paragraph for new spacing pressure.

Adobe InDesign guidance

Use Type > Insert White Space for explicit characters and reveal hidden characters during QA. Verify that fonts and export formats preserve the chosen space.

How Avellio detects it

Avellio emits UNIT_SPACE for recognized number–unit pairs and PREPOSITION for supported Czech/Polish short-word cases.

Action safety

Guarded recognized unit pairs can enter Safe Clean; exact Czech/Polish short-word cases require Review Queue.

Check this automatically in Adobe InDesign

Language and locale differences

CZ

Selected Czech one-letter words should not be stranded at line end.

PL

Selected Polish one-letter words receive comparable guarded treatment.

FRFR CHFR CA

French punctuation and guillemets may require NBSP or NNBSP according to locale and house style.

Compare all published language and locale guides.

Authoritative references

  1. Unicode Standard Annex #14 — Unicode Line Breaking AlgorithmUnicode standard
  2. Avellio User Manual — Locale profile referenceAvellio product source
  3. Avellio User Manual — The Action LayerAvellio product source

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.