Complete the series: ZY1,AB3,XW5, CD,_____?

Himachal Pradesh Staff Selection Commission (HPSSC) released the schedule of screening test to be conducted for selection to the posts of Supervisor LDR Post Code-561. Screening test was held on 28.05.2017 in evening session (from 02.00 PM to 04.00 PM). This is for ICDS department post.