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Testable requirements for "suitable shape" and "adequate size" of text

The following proposal has come from Mitchell Evan (TPG Interactive):

Issue #111 (closed) includes this EAA requirement:

(v) presenting in fonts of adequate size and suitable shape, taking into account foreseeable conditions of use and using sufficient contrast, as well as adjustable spacing between letters, lines and paragraphs

I would like to request that EN 301 549 address two specific aspects of the above requirement.

1. Suitable shape

Is the requirement that text have "suitable shape" already fully or partially addressed by the following?

  • "font type" mentioned in a note for 7.1.4 Captions Characteristics
  • "font type" mentioned in 11.7 User Preferences

If already fully addressed, please provide additional informative notes explaining how these clauses can be applied to determine whether text has "suitable shape".

If not already fully addressed, I request that EN 301 549 provide a testable requirement for "suitable shape".

2. Adequate size

Currently, it is reasonable to expect that meeting these existing EN 301 549 clauses would result in "adequate size" for most text:

  • Chapters 9, 10, and 11 inclusion of WCAG SC 1.4.4 Resize Text
  • Chapters 9, 10, and 11 inclusion of WCAG SC 1.4.5 Images of Text. (This is relevant because 1.4.4 has an exception for images of text. Depending on the resize mechanism, images sometimes don't resize along with regular text. In some contexts, images could even become smaller as regular text is enlarged.)
  • 5.1.4 Functionality closed to text enlargement
  • 7.1.4 Captions characteristics
  • 11.7 User preferences

However, outside of closed functionality, nothing in the existing clauses requires text to have a minimum size before resizing. For text that's unusually small before the user enlarges it, the existing requirements alone cannot achieve what would reasonably called an "adequate size." Thus, the "adequate size" requirement of EAA goes beyond existing requirements.

Proposed:

Until EN 301 549 says otherwise, I have provisionally interpreted the "Adequate size" requirement as follows. I propose that EN 301 549 address this EAA requirement with similar specificity. This is not phrased as it would be in EN 301 549, but it conveys the intention.

(start of provisional interpretation)

In instructions for products and services, text shall have adequate size.

As a reasonable measure of "adequate size," all text shall be presentable with a size equivalent to CSS font-size: 18px or larger. Adequate size may be achieved in the default size of the text, or by using an available resize mechanism that is not assistive technology (as described in WCAG SC 1.4.4 Resize Text) to enlarge the text to 200% of its default size. Example: HTML text with CSS font-size: xx-small, when zoomed to 200%, is presented with a size equivalent to CSS font-size: 18px and would be considered to have adequate size.

The "adequate size" requirement applies to text and images of text, including open and closed captions in video, except for text that is pure decoration.

Note: The following additional measures are recommended for an improved user experience:

  • It is recommended that most text be equivalent to at least CSS font-size: 16px without zooming. (This is the default size of text in most browsers.)
  • It is recommended that all text be equivalent to at least CSS font-size: x-small without zooming.

(end of provisional interpretation)