Officer Candidate School or Officer Cadet School (OCS) is an institution, which train candidate of military officer in order for them to gain a commission in Imperial Army. This school also serve as the next level of education after Cadet School.
There are two known route to enter OCS shown in the series, the first is the path Tanya Degurechaff took. Individual who volunteer to serve in army is given privilege to enter the school automatically after Cadet School. The other way for a personnel to enroll is through recommendation. Viktoriya Ivanovna Serebryakov is such case, she was recommended by Tanya Degurechaff and Ihlen Schwarzkopf for officer course.
Officer training given by OCS focus on military skills and leadership. The regular course takes about two years to complete and during war period the course is accelerated and completed in less than a year. The students are divided by year from the most senior first classer to junior fourth classer. As part of their training, accomplished student like Tanya Degurechaff in fourth class is tasked to be drill instructor for new students.
Upon completion of deployment training, the cadet would be commissioned as Second Lieutenant. The lowest rank of commissioned officer.