def DoesIDExist(tag_name):
    """
    Determines if a fully-qualified site.service.tag eDNA tag exists
    in any of the connected services.

    :param tag_name: fully-qualified (site.service.tag) eDNA tag
    :return: true if the point exists, false if the point does not exist

    Example:

    >>> DoesIDExist("Site.Service.Tag")

    """
    # the eDNA API requires that the tag_name be specified in a binary format,
    # and the ctypes library must be used to create a C++ variable type.
    szPoint = c_char_p(tag_name.encode('utf-8'))
    result = bool(dna_dll.DoesIdExist(szPoint))
    return result