The current Secure Shell protocol and current clients do not transfer any information about the files to be transferred, only the file contents as a byte stream. This is sufficient for Unix-type files if the sender and receiver use the same CCS.
SSH Tectia Server for IBM z/OS needs more information: which transfer format to use, what code sets are involved, and what the file characteristics are. When SSH Tectia is used at both ends, the information can be relayed by using the Site commands of scpg3 and sftpg3, or read from environment variables. When a third-party Secure Shell client is used together with SSH Tectia Server for IBM z/OS, the information can be either encoded in the filename (advice string), read from a file transfer profile, or read from environment variables.
Using the Site command is described in Site Command (and Site Command Examples with Other Clients). Using the environment variables is described in File Transfer Environment Variables for the Clients and File Transfer Environment Variables for the Server. For information on using third-party clients, see Advice String and File Transfer Profiles.