According to Gérard de Vaucouleurs' classification scheme, what do the E0 and E7 designations represent?

Answer

E0 represents the most spherical, and E7 denotes the most elongated.

In the E0 to E7 system, E0 galaxies are classified as the most spherical or roundest systems, while E7 galaxies are classified as the most flattened or elongated.

According to Gérard de Vaucouleurs' classification scheme, what do the E0 and E7 designations represent?
Spacegalaxiesastronomystructureelliptical galaxiesgalaxy classificationelliptical