extern int get_pressure_units(unsigned int mb, const char **units);
extern double get_depth_units(unsigned int mm, int *frac, const char **units);
extern double get_volume_units(unsigned int mm, int *frac, const char **units);
extern double get_temp_units(unsigned int mm, const char **units);
extern int get_pressure_units(unsigned int mb, const char **units);
extern double get_depth_units(unsigned int mm, int *frac, const char **units);
extern double get_volume_units(unsigned int mm, int *frac, const char **units);
extern double get_temp_units(unsigned int mm, const char **units);