Hi Shibli,
EOS – End of Selection Codes.
For the MSC/VLR/SSF/gsmSSF EOS you have to look the CODS (MML commands), PODS (Printouts) and OPI (MML operations) documentation set.
MML is the man machine language that is used by the Switch (Stored Program Control) node.
VBR/ Wallis Dudhnath