 Causative or intensive forms are formed with the doubled D-stem, and it gets its name from the doubled-middle radical that is characteristic of this form.The doubled middle radical is also characteristic of the present, but the forms of the D-stem use the secondary conjugational affixes, so a D-form will never be identical to a form in a different stem.The Š-stem is formed by adding a prefix "š-", and these forms are mostly causatives.