/usr/lib/swipl/library/system.pl
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 system_mode(+Boolean) is det
Switch the system into system or user mode. When in system mode, system predicates loose most of their special properties, so it becomes possible to trace and even redefine them.
deprecated
- New code should use the prolog flag access_level.
ClioPatria (version V3.1.1-59-g7b9a7a3)