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It is not uncommon due to changes in taxonomy for a single name to be used to cover different contents. For instance, in the traditional Wetmore classification of birds, the order included a group of families of long-legged wading birds, including and . In the Sibley & Ahlquist classification based on DNA-DNA hybridisation, the was expanded to cover a much larger group of taxa, including representatives from Wetmore's orders , , , etc. Therefore, use of the name "Ciconiiformes" could possibly cause confusion as to which set of taxa is being indicated. Where that is likely to be a problem, the word sensu (Latin, "in the sense of") can be used. Thus, Ciconiiformes sensu Wetmore indicates the former meaning, while Ciconiiformes sensu Sibley & Ahlquist indicates the latter.
In many such cases, there may be two primary competing uses of the term, with the coverage in one meaning entirely contained within the coverage of the other meaning. In these cases, authors may use the terms "sensu stricto" (in the narrow sense) and "sensu lato" (in the broad sense) to distinguish the two. Hence, in the above example, Wetmore's Ciconiiformes would be Ciconiiformes sensu stricto, while Sibley & Ahlquist's would be Ciconiiformes sensu lato.