FcObjectSetAdd (3) - Linux Manuals
FcObjectSetAdd: Add to an object set
NAME
FcObjectSetAdd - Add to an object set
SYNOPSIS
#include <fontconfig/fontconfig.h>
FcBool FcObjectSetAdd (FcObjectSet *os, const char *object);
DESCRIPTION
Adds a property name to the set. Returns FcFalse if the property name cannot be inserted into the set (due to allocation failure). Otherwise returns FcTrue.