What does the designation $ ext{E}7$ signify for an elliptical galaxy?

Answer

The most elongated or flattened shape

The shapes of elliptical galaxies are described from $ ext{E}0$ (nearly perfectly spherical) to $ ext{E}7$, which represents the most elongated or flattened shape.

What does the designation $	ext{E}7$ signify for an elliptical galaxy?
classificationgalaxiesastronomyproperties