h6. [[Programmer's Reference Manuals]] h6(. » [[Service Calls]] h6((. » Service_PreModeChange h2. Service_PreModeChange h5. (Service &4D) |_<^{width:4em}. Entry | | |<^. R1 |<^. 77 (&4D)| |<^. R2 |<^. [[Mode Specifier]] | h4. Case 1 – Module has no objection |_<^{width:4em}. Exit | | |<^. R1 |<^. Preserved to pass on| |<^. R2 |<^. Preserved to pass on| h4. Case 2 – Module objects, and takes alternative action |_<^{width:4em}. Exit | | |<^. R1 |<^. 0 (claim service)| |<^. R2 |<^. 0| h4. Case 3 – Module objects, and returns an error |_<^{width:4em}. Exit | | |<^. R0 |<^. Pointer to [[SWI Error Block|error block]]| |<^. R1 |<^. 0 (claim service)| h4. Case 4 – Module wishes to substitute an alternative mode |_<^{width:4em}. Exit | | |<^. R1 |<^. Preserved to pass on| |<^. R2 |<^. New [[Mode Specifier]]| h4. Use This service allows a module to object to a mode change, or substitute a different mode. h4. Notes [[Service_ModeTranslation]] offers a better method to support new monitor types. h4. See also * [[Service Calls]] * [[Service_ModeChange]] * [[Service_ModeTranslation]] * [[Screen Modes]] * [[SWI Error Block]]