The SIGNAL keyword was reserved for OS/2 systems (protected mode). See the example for more information about how and why it is used. {{PageSyntax}} :: [[ON]] SIGNAL(number) [[GOSUB]] line :: SIGNAL(number) [[ON]] *'''[[Keywords currently not supported by QB64|Currently NOT supported in QB64!]]''' * It will only work with compiler 6.00 and 6.00b and Basic PDS 7.00 when compiling in protected mode under OS/2. In all other situations, a SIGNAL statement results in an "Advanced feature unavailable" error message. ''Example:'' {{CodeStart}} '' '' {{Cl|PRINT}} "This program traps CTRL+BREAK in OS/2. Try it." {{Cl|ON}} SIGNAL(4) {{Cl|GOSUB}} trap {{Cl|SIGNAL}}(4) {{Cl|ON}} 10 a$ = {{Cl|INKEY$}} {{Cl|IF...THEN|IF}} a$ = "" {{Cl|THEN}} {{Cl|GOTO}} 10 {{Cl|END}} trap: {{Cl|PRINT}} "CTRL+BREAK trapped. Press any key to quit" {{Cl|RETURN}} '' '' {{CodeEnd}} ''Output:'' It returns the following when Ctrl-Break is pressed {{OutputStart}} This program traps CTRL+BREAK in OS/2. Try it. CTRL+BREAK trapped. Press any key to quit {{OutputEnd}} ''Error message in QB4.5 if not using OS 2:'' {{OutputStart}} Advanced feature unavailable {{OutputEnd}} ''Source:'' Microsoft KB41389 [[http://support.microsoft.com/kb/41389]] ''See also:'' * [[ON KEY (n)]] {{PageNavigation}}