def data_ref_type_str(dref_enum):
    """
    Translate an ``enum DataRefTypes`` value into a string representation.
    """
    if dref_enum == 0x9000:
        return 'unknown'
    elif dref_enum == 0x9001:
        return 'integer'
    elif dref_enum == 0x9002:
        return 'fp'
    else:
        return 'INVALID'