Each process has a code page tag maintained by OS/2. A code page tag is the identifier of the current code page for the process.

A child process inherits the code page tag of its parent. The default code page for the first process in a session is the same as the session code page. The default code page for a new session is the primary code page specified in the CODEPAGE configuration statement.

To change the code page tag of a process, call DosSetProcessCp. This will not change the process code page tag of its parent or any child process.