Variable: scalable-fonts-allowed

Allowed scalable fonts.
A value of nil means don't allow any scalable fonts.
A value of t means allow any scalable font.
Otherwise, value must be a list of regular expressions. A font may be
scaled if its name matches a regular expression in the list.
Note that if value is nil, a scalable font might still be used, if no
other font of the appropriate family and registry is available.