The ability to snap two windows side-by-side automatically.
hdiutil create -o /tmp/ElCapitan -size 8000m -layout SPUD -fs HFS+J os x el capitan iso
An ISO file is a disk image format commonly used for installation media. While Apple typically distributes macOS as an application bundle (Install OS X.app) or a DMG file, an ISO is often required for: The ability to snap two windows side-by-side automatically