def delCorrtagWCS(thdr):
    """Delete table WCS keywords.

    The function returns a copy of the header with table-specific WCS keywords
    deleted.  This is appropriate when creating an x1d table from a corrtag
    table.

    Parameters
    ----------
    thdr: pyfits Header object
        A header for a BINTABLE extension.

    Returns
    -------
    hdr: pyfits Header object
        A copy of thdr, with certain table WCS keywords deleted.
    """
    hdr = thdr.copy()
    tkey = ['TCTYP2', 'TCRVL2', 'TCRPX2', 'TCDLT2', 'TCUNI2', 'TC2_2',
        'TC2_3', 'TCTYP3', 'TCRVL3', 'TCRPX3', 'TCDLT3', 'TCUNI3', 'TC3_2',
        'TC3_3']
    for keyword in tkey:
        if keyword in hdr:
            del hdr[keyword]
    return hdr
