h6. [[Programmer's Reference Manuals]] h6(. » System Control Handlers table(bordered). |_<^{width:4em}. #|_<^. Meaning|_<^. [[OS_ChangeEnvironment]] R1 value |_<^. R2 value |_<^. R3 value | |<^. 0|<^. [[Memory Limit Handler|Memory limit]]|<^. Memory limit |<^. Unused |<^. Unused | |<^. 1|<^. [[Undefined Instruction Handler|Undefined instruction]]|<^. Handler code |<^. Unused |<^. Unused | |<^. 2|<^. [[Prefetch Abort Handler|Prefetch abort]]|<^. Handler code |<^. Unused |<^. Unused | |<^. 3|<^. [[Data Abort Handler|Data abort]]|<^. Handler code |<^. Unused |<^. Unused | |<^. 4|<^. [[Address Exception Handler|Address exception]]|<^. Handler code |<^. Unused |<^. Unused | |<^. 5|<^. Other exceptions (reserved)|<^. Unused |<^. Unused |<^. Unused | |<^. 6|<^. [[Error Handler|Error]]|<^. Handler code |<^. Handler R0 |<^. Error buffer | |<^. 7|<^. [[CallBack Handler|CallBack]]|<^. Handler code |<^. Handler R12 |<^. Register dump buffer | |<^. 8|<^. [[BreakPoint Handler|BreakPoint]]|<^. Handler code |<^. Handler R12 |<^. Register dump buffer | |<^. 9|<^. [[Escape Handler|Escape]]|<^. Handler code |<^. Handler R12 |<^. Unused | |<^. 10|<^. [[Event Handler|Event]]|<^. Handler code |<^. Handler R12 |<^. Unused | |<^. 11|<^. [[Exit Handler|Exit]]|<^. Handler code |<^. Handler R12 |<^. Unused | |<^. 12|<^. [[Unused SWI Handler|Unused SWI]]|<^. Handler code |<^. Handler R12 |<^. Unused | |<^. 13|<^. [[Exception Registers Block|Exception registers]]|<^. Register dump buffer |<^. Unused |<^. Unused | |<^. 14|<^. [[Application Space Handler|Application space]]|<^. Memory limit |<^. Unused |<^. Unused | |<^. 15|<^. [[Currently Active Object Handler|Currently active object]]|<^. CAO pointer |<^. Unused |<^. Unused | |<^. 16|<^. [[UpCall Handler|UpCall]]|<^. Handler code |<^. Handler R12 |<^. Unused | |<^. 32|<^. [[Branch Through 0 Handler]]|<^. Handler code |<^. Unused |<^. Unused | |<^. 33|<^. [[Command Line Area]]|<^. Unused |<^. Size of command line area |<^. Command line area | h6. Controlling sources: "Hdr:EnvNumbers":https://gitlab.riscosopen.org/RiscOS/Sources/Programmer/HdrSrc/-/blob/master/hdr/EnvNumbers managed by the "allocations manager":/content/allocate h4. See also * [[OS_ChangeEnvironment]]