PK_FCURVE_t

This type represents a Foreign CURVE; that is, one implemented in an
externally supplied parametric evaluator.

Used in:

PK_FCURVE_ask
PK_FCURVE_create

A foreign curve is a type of curve (PK_CLASS_fcurve is a subclass of
PK_CLASS_curve).

The fcurve is defined by data contained in a PK_FCURVE_sf_t