Gendl also sets *read-default-float-format* to 'double-float, and expects it to be set that way for compiling any Gendl/GDL application code (all the internal operations for points, vectors, transforms, etc are expected to deal in double-floats). 

That is the only non-ANSI-compliant thing in Gendl, as far as I know. 

If there is a reasonable way to back out of this to make Gendl 100% ANSI compliant, I'd be interested to look into it. But the current situation is that users expect double-float to be the default when working with Gendl.