= Taxonomic class
A <taxonomic class> is a <taxonomic rank> conventionally below a <taxonomic phylum> and above a <taxonomic order>. A particular class is a <taxon> at that level. For example, <Mammalia> is the class of <mammals>, and <Carnivora> is one of its constituent orders.<Biology 2e by Mary Ann Clark and others>[section 20.1, Classification Levels and Figures 20.5–20.6]{ref}
The hierarchy makes several statements simultaneously: an individual cat belongs to <Mammalia>, <Carnivora> and <Felidae>, at class, order and family ranks respectively. These nested memberships describe increasing specificity. They do not give three independent estimates of the cat's identity.
Consider a constructed sampling table with two classes, each represented by twelve sampled <species>. The first has two sampled orders containing six species each; the second has three containing four each. The class totals agree, while the within-class distribution differs. Class-level aggregation preserves the total and discards that structure. Nor would twelve sampled species establish twelve species in the complete class: sampling coverage is a separate issue.
A <taxonomic class> need not have a fixed number of orders, individuals or species. Its rank also does not specify a fixed age or a numerical amount of genetic divergence. Those are additional biological quantities or hypotheses that require evidence beyond the hierarchical label.
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