A more thorough explanation:

citatory (sI-tə-tor-ee), adj. Of, relating to, or having the power of a citation or summons letters citatory.

The term citatory refers to something that has the power of a citation or summons. This means that it can be used to legally require someone to appear in court or to provide evidence in a legal case.

• A citatory letter was sent to the witness, requiring them to appear in court to testify.
• The judge issued a citatory order, requiring the defendant to appear in court on a specific date.

These examples illustrate how a citatory letter or order can be used to legally require someone to appear in court or to provide evidence. In both cases, the citatory document has the power to compel the recipient to take action.