 
 
 
| Flag | Values | Description | ISO | 
| true / false | are integers
bounded ? | Y | |
| an integer | greatest integer | Y | |
| an integer | smallest integer | Y | |
| toward_zero
 down | rnd(X) = integer part of X rnd(X) = ëXû (section 6.6.1) | Y | |
| an integer | maximum arity for compound terms (255) | Y | |
| an integer | maximum number of atoms | N | |
| an integer | maximum number of streams | N | |
| an integer | maximum number of successive ungets | N | |
| an atom | name of the Prolog system | N | |
| an atom | version number of the Prolog system | N | |
| an atom | date of the Prolog system | N | |
| an atom | copyright message of the Prolog
system | N | 
| Flag | Values | Description | ISO | 
| on / off | is
character conversion activated ? | Y | |
| on / off | is the debugger
activated ? | Y | |
| on / off | warn
about named singleton variables ? | N | |
| on / off | strict ISO
behavior ? | N | |
| atom chars codes | a double quoted constant is returned as:
 an atom a list of characters a list of character codes | Y | |
| error warning fail | a predicate calls an unknown procedure:
 an existence_error is raised a message is displayed then fails quietly fails | Y | |
| error warning fail | a predicate causes a syntax error:
 a syntax_error is raised a message is displayed then fails quietly fails | N | |
| error warning fail | a predicate causes an O.S. error:
 a system_error is raised a message is displayed then fails quietly fails | N | 
| Flag is a variable | instantiation_error | |
| Value is a variable | instantiation_error | |
| Flag is neither a variable nor an atom | type_error(atom, Flag) | |
| Flag is an atom but not a valid flag | domain_error(prolog_flag, Flag) | |
| Value is inappropriate for Flag | domain_error(flag_value, Flag+Value) | |
| Value is appropriate for Flag but flag Flag is not modifiable | permission_error(modify, flag, Flag) | |
| Flag is neither a variable nor an atom | type_error(atom, Flag) | |
| Flag is an atom but not a valid flag | domain_error(prolog_flag, Flag) | |
| Functor is a variable | instantiation_error | |
| Arity is a variable | instantiation_error | |
| Functor is neither a variable nor an atom | type_error(atom, Functor) | |
| Arity is neither a variable nor an integer | type_error(integer, Arity) | |
| Functor is neither a variable nor an atom | type_error(atom, Functor) | |
| Arity is neither a variable nor an integer | type_error(integer, Arity) | |
| FileName is a variable | instantiation_error | |
| FileName is neither a variable nor an atom | type_error(atom, FileName) | |
| an operating system error occurs and the value of the os_error Prolog flag is error (section 6.22.1) | system_error(atom explaining the error) | |
 
 
