Hasan Files a Writ

"No. 21-0003/AR. Nidal M. Hasan, Petitioner v. United States Army Court of Criminal Appeals, Respondent and United States, Real Party In Interest. CCA 20200436. Notice is given that a petition for extraordinary relief in the nature of writ of prohibition and brief were filed under Rule 27(a) on this date." Anyone know what this is about?