हस्तिनोऽश्वा रथाः पत्तयश्चानुपृष्ठमप्रतिहतः ॥ कZ_१०.६.४१ ॥
hastino 'śvā rathāḥ pattayaś cānupṛṣṭham apratihataḥ
In the ‘Apratihata’ array, elephants, cavalry, chariots, and infantry are arranged successively, one behind another (in depth).
Apratihata places shock assets (elephants) foremost to rupture the enemy early; Acala begins with infantry, implying a more controlled, attritional or screening approach.