These type of sets can be classified using the arithmetical hierarchy.

Two-year colleges are classified using a different scale than four-year and higher institutions.

Resources were classified using a scheme based on Ei codes.

Cards are classified using the colors blue, red, yellow, green or pink (rare).

These can be classified then using the second derivative test from basic calculus.

Goods can be classified using a heading falling under Rule 1.

Most briefs are classified using a limited number of client/subject headings.

Lung cancers have been historically classified using two major paradigms.

Calls are classified using a hierarchical model known as "problem profiles."

Establishments are classified using a stars and sun system to help visitors choose their accommodations.