A fontspec specifies a font and is used in some wd and gl2 commands. A fontspec is:
name size [italic] [bold] [underline] [angle]
"lucida console" 15.5 italic
The size is in points, can be fractional, and must be positive.
The angle style gives an angle in 10ths of degrees clockwise from the baseline. For example:
glfont 'arial 240 angle900'