Where a subsequent spelling differs from the original, it can be either:
- a “mandatory change” if needed to correct the ending (Art. 34) such as when a species name is combined with a different genus, it may need to change ending to agree with the gender of the genus. This is effectively the same name and retains the same author and date.
- an “emendation” if a demonstrably intentional change (Art. 33.2) not required by Article 34. An emendation may be:
- a “justified emendation” (Art. 33.2.2) if corrected under article 32.5. This retains the same author and date as the original name.
- o or an “unjustified emendation” (Art. 33.2.3) if not corrected under article 32.5. An unjustified emendation is available with its own author and date and is usually a junior synonym of the name in its original spelling. Rarely an unjustified emendation can become a justified emendation if in prevailing usage (Art. 18.104.22.168)
- or if neither a mandatory change or emendation, it is an “incorrect subsequent spelling” (Art. 33.3). An incorrect subsequent spelling is not an available name. Rarely it can become the correct original spelling if in prevailing usage (Art. 33.3.1).
More detail on the spellings of names can be found in Articles 11 and 25-34; species group names in Articles 11.9 and 31; genus group names in Article 11.8; and family group names in Article 11.7 and 29.