A distribution interest can be classified in three ways:
A discretionary interest may be evidenced by permissive language such as "may make distributions" or it may be evidenced by mandatory distribution language that is negated by the discretionary language of the trust, such as "the trustee shall make distributions in the trustee's sole and absolute discretion." An interest that includes mandatory distribution language such as "shall" but is subsequently qualified by discretionary distribution language shall be classified as a discretionary interest and not as a support or a mandatory interest. A discretionary interest is any interest that is not a mandatory or a support interest.
SDCL 55-1-38