These functions are no longer available.
ud_units: Use as_units instead.
as.units: Use as_units instead.
make_unit: Use as_units instead.
parse_unit: Use as_units instead.
as_cf: Use deparse_unit instead.
install_symbolic_unit: Use install_unit instead.
remove_symbolic_unit: Use remove_unit instead.
install_conversion_constant: Use install_unit instead.
install_conversion_offset: Use install_unit instead.