Typically, pore sizes have been separated into three size categories, micropores (<2 nm), mesopores (2 to 50 nm), and macropores (over 50 nm).
In its turn, profiles with the bulk-film region have been separated into three different types, referred to as the "membrane", "electroncounterion" and "semiconductor" forms.
RHT morphology has been separated into three types based on results from a multicenter questionnaire on echocardiographically detected RHT [1]: type A - thin, highly mobile, serpiginous; type B - immobile and ovoid shaped; type C - had characteristics of both A and B (highly mobile but globular).
In the past, the species (when it was known as Calvatia utriformis) has been separated into three varieties (C. utriformis var. utriformis, C. utriformis var. hungarica and C. utriformis var. gruberi) based on differences in the ornamentation of the exoperidium (outer tissue layer of the wall, or peridium) and spores.
Radiation encephalopathy has been separated into three stages: acute reaction, early-delayed reaction, and late-delayed reaction (Sheline, 1977).
The interactions have been separated into three groups: those coming from each of the two benzene rings and those arising from interactions of the core of the substrate.
