Those who read braille signs are often inexperienced, and the rounded or domed dots assist them. Upper-case letter indicators generally slow readers. Letter-height limits are more specific, based on the height of the sign and the distance from which it will be read. The higher it is on the wall and the further away from the reader, the larger the text must be. Specs for pictograms and symbols of accessibility remain essentially the same, but the pictogram standards are more easily understood.
Visibility is the major concern.
ANSI-1992 added some, but ignored viewing distance. Equivalent facilitation These ratios, designed to prevent extended or condensed type, are intended to increase legibility of tactile letters. This term comes into play when space problems or characteristics of the intended sign's audience limit the effectiveness of normal standards. People who frequent certain buildings may have limited reach or be confined to wheelchairs. The law permits barrier removal in a problem-solving fashion.