def construct_hdf5_pre_and_post(chd_meta):
    """
    Standardize/Centralize hdf5 image filename production
    :param chd_meta: image meta dictionary. Output of euv_utils.py - get_metadata()
    :return: prefix, postfix, and extension strings
    """
    prefix = chd_meta['instrument'].lower().replace('-', '') + '_lvl2'
    postfix = str(chd_meta['wavelength'])
    extension = 'h5'

    return prefix, postfix, extension