Any time the leg is straight, the main focus is on the large, outer calf muscle called the gastrocnemius. (sixstarpro.com)
Single legged standing calf raises build and strengthen the superficial, outer calf muscle — the gastrocnemius. (ptinto.com)
Stand straight with your feet wide apart, toes pointing either straight (equal emphasis on all calve muscles), inwards (emphasis on the inner calves) or outwards (emphasis on the outer calves), and raise your heels off the floor as you exhale by contracting the calves. (fitnessandpower.com)