5.1.4. Functionality closed to text enlargement

Where any functionality of ICT is closed to the text enlargement features of platform or assistive technology, the ICT shall provide a mode of operation where the text and images of text necessary for all functionality is displayed in such a way that a non-accented capital "H" subtends an angle of at least 0,7 degrees at a viewing distance specified by the supplier.

The subtended angle, in degrees, may be calculated from:

Ψ = (180 x 60 x H) / (π x D)

Where:

•  ψ is the subtended angle
•  H is the height of the text
•  D is the viewing distance.
•  D and H are expressed in the same units

Notes

The intent is to provide a mode of operation where text is large enough to be used by most users with low vision.

Testing methods