On Scalable Text
http://www.uiaccess.com/scaletext.html

Henry, Shawn Lawton
UI Access
2002

Abstract:

In order to provide scalable text, make textual information text (rather than images), and use relative text sizes (rather than absolute). Scalable text is important for people with low vision. The basics of providing scalable text are very simple. However, strict design requests can pose challenges.