def _load_derived_core_properties_txt():
    """Load derived core properties from Blocks.txt."""
    with open_unicode_data_file("DerivedCoreProperties.txt") as dcp_txt:
        dcp_ranges = _parse_code_ranges(dcp_txt.read())

    for first, last, property_name in dcp_ranges:
        for character_code in range(first, last + 1):
            try:
                _core_properties_data[property_name].add(character_code)
            except KeyError:
                _core_properties_data[property_name] = {character_code}