SICStus 3.8 supports standard Prolog, adhering to the International
Standard ISO/IEC 13211-1 (PROLOG: Part 1—General Core)
(http://webstore.ansi.org/ansidocstore/product.asp?sku=INCITS%2FISO%2FIEC+13211%2D1%2D1995). At the same
time it also supports programs written in earlier versions of SICStus.
This is achieved by introducing two execution modes
sicstus. Users can change between the modes using the Prolog flag
language. Main issues:
sicstusexecution mode is practically identical to 3.7.1, except for minor changes in error term format.
isomode is fully compliant with ISO standard, but no strict conformance mode is provided.
sicstusexecution mode, unless they conflict with existing SICStus predicates or functions. This expansion of the language carries a remote risk of name clashes with user code.