css3-fonts: <integer>, <length>, <number>, <percentage>, <string> used but not defined

In various parts of [1] appear uses of the following property value
expressions:

   - <integer>
   - <length>
   - <number>
   - <percentage>
   - <string>

However, nowhere in [1] appears a definition or a normative reference to a
definition of these expressions.

Suggest that an explicit reference be made to their definitions in [2].

G.

[1] http://dev.w3.org/csswg/css3-fonts/
[2] http://www.w3.org/TR/css3-values/