- The appropriate rank of a nothotaxon is that of the postulated or known parent taxa.
- If the postulated or known parent taxa are of unequal rank the appropriate rank of the nothotaxon is the lowest of these ranks.
- When a nothotaxon is designated by a name in a rank inappropriate to its hybrid formula, the name is incorrect in relation to that hybrid formula but may nevertheless be correct, or may become correct later (see also Art. 52 Note 3).
- The combination Elymus ×laxus (Fr.) Melderis & D. C. McClint. (1983), based on Triticum laxum Fr. (1842), was published for hybrids with the formula E. farctus subsp. boreoatlanticus (Simonet & Guin.) Melderis × E. repens (L.) Gould, so that the combination is in a rank inappropriate to the hybrid formula. It is, however, the correct name applicable to all hybrids between E. farctus (Viv.) Melderis and E. repens.
- Radcliffe-Smith incorrectly published the nothospecific name Euphorbia ×cornubiensis Radcl.-Sm. (1985) for E. amygdaloides L. × E. characias subsp. wulfenii (W. D. J. Koch) Radcl.-Sm., although the correct nothospecific designation for all hybrids between E. amygdaloides and E. characias L. is E. ×martini Rouy (1900); later, he published the appropriate combination E. ×martini nothosubsp. cornubiensis (Radcl.-Sm.) Radcl.-Sm. (in Taxon 35: 349. 1986). However, the name E. ×cornubiensis is potentially correct for hybrids with the formula E. amygdaloides × E. wulfenii W. D. J. Koch.