The system is organized by generation, i.e., generations are grouped separately.

Organic compounds containing bonds of carbon to nitrogen, oxygen and the halogens are not normally grouped separately.

Airborne, armored, cavalry, infantry, and mountain divisions are grouped separately.

Pituitary tumors occur most frequently in the sellar region, but they are traditionally grouped separately.

Many lines of descent from the major rishis were later grouped separately.

Students are grouped separately in Mathematics and English in order to challenge and provide support according to individual needs.

Astaire also created a number of routines where he danced in turn with a sequence of partners and these are grouped separately.

The various animals have been grouped separately, such camels, birds, red gaur, tigers, crocodiles, and others.

Today, Military Engineers are grouped separately within each of the armed services.