• XCS yag3m is the yag that sits on the main CXI line before(?) the LODCM. The "m" stands for "main" so then xcs yag3 sits on the periscope line while yag3m sits on the main line.
  • It is typically used to verify the trajectory before the XRT mirror is inserted to bring the beam to MFX. If the mirror is inserted you won't see anything on this YAG.