Business rules manual
RGAA v4.1.2
Theme 1: Images
Rule 1.3.6

Rule 1.3.6

Summary

This test consists in checking whether the textual alternative of each object svg that convey information is relevant.

Business description

Criterion

1.3

Test

1.3.6

Description

Pour chaque image vectorielle (balise <svg>) porteuse d’information , ayant une alternative textuelle , cette alternative est-elle pertinente (hors cas particuliers)?

  • S’il est présent, le contenu de l’élément <title> est pertinent
  • S’il est présent, le contenu de l’attribut WAI-ARIA aria-label est pertinent
  • S’il est présent, le passage de texte associé via l’attribut WAI-ARIA aria-labelledby est pertinent.

Cas particuliers (1.3)

Il existe une gestion de cas particuliers lorsque l’image est utilisée comme CAPTCHA ou comme image-test . Dans cette situation, où il n’est pas possible de donner une alternative pertinente sans détruire l’objet du CAPTCHA ou du test, le critère est non applicable. Note le cas des CAPTCHA et des images-test est traité de manière spécifique par le critère 1.4.

Level

A

Technical description

Scope

Page

Decision level

Decidable with marker

Algorithm

Selection

Set1

All the <svg> tags, not within a link and not identified as captcha (see Notes about captcha detection)

Set3

All the elements of Set1 identified neither as informative image, nor as decorative image by marker usage (see Notes for details about detection through marker)

Set4

All the elements of Set2 with a textual alternative (see Notes for details about textual alternative detection).

Set5

All the elements of Set3 with a textual alternative (see Notes for details about textual alternative detection).

Process

None

Analysis

Not Applicable

The page has no <svg> tag with a textual alternative (Set2 is empty)

Failed

At least one <svg> tag, identified as informative, has a textual alternative that is not pertinent (Test1 returns false for at least one element)

Pre-qualified

In all other cases

Notes

Textual alternative detection

The textual alternative can be set by the presence of any the following elements :

  • Text associated via the aria-labelledby WAI-ARIA attribute
  • Presence of a not empty aria-label WAI-ARIA attribute
  • Presence of a not empty <title> child tag That order has to be respected to compute the textual alternative.

For instance, if some text associated via the aria-labelledby WAI-ARIA attribute and an aria-label WAI-ARIA attribute are both present, the content of the text associated via the aria-labelledby WAI-ARIA attribute is considered as the textual alternative.

Textual alternative relevancy

The content of the textual alternative is seen as not relevant if :

  • empty
  • only composed of non-alphanumerical characters
  • it has an extension of image type (loaded by the nomenclature named ImageFileExtensions composed of : jpg, gif, jpeg, png, bmp)

Markers

Informative images markers are set through the INFORMATIVE_IMAGE_MARKER parameter.

Decorative images markers are set through the DECORATIVE_IMAGE_MARKER parameter.

The value(s) passed as marker(s) will be checked against the following attributes:

  • class
  • id
  • role

Captcha detection

An element is identified as a CAPTCHA when the “captcha” occurrence is found :

  • on one attribute of the element
  • or within the text of the element
  • or on one attribute of one parent of the element
  • or within the text of one parent of the element
  • or on one attribute of a sibling of the element
  • or within the text of a sibling of the element

Files

Rule 1.3.5Rule 1.3.7