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Footnotes

note-1
Quintus is a trademark of Quintus Computer Systems Inc., USA
note-2
BIM is a trademark of BIM sa/nv., Belgium
note-3
One could choose words, defining words as a sequence of alpha-numeric characters and the word separators as anything else, but one could also choose Prolog arguments
note-4
This implies the system can run out of local stack in debug mode, while no problems arise when running in non-debug mode.
note-5
These marks do not suggest instantiation (e.g. var(+Var)).
note-6
It does work for normal loading, but not for qcompile/1.
note-7
Strings might be considered atoms in future versions. See also section 3.23
note-8
In fact the variables are compared on their (dereferenced) addresses. Variables living on the global stack are always < than variables on the local stack. Programs should not rely on the order in which variables are sorted.
note-9
BUG: The system should have a special type for pointers, thus avoiding the Prolog user having to worry about consistency matters. Currently some simple heuristics are used to determine whether a reference is valid.
note-10
For example, using the immediate update view, no call to a dynamic predicate is deterministic.
note-11
BUG: Backtracking does not give other aliases.
note-12
Note that Edinburgh Prolog defines fileerrors/0 and nofileerrors/0. As this does not allow you to switch back to the old mode I think this definition is better.
note-13
In version 1.2 instantiation faults led to error messages. The new version can be used to do type testing without the need to catch illegal instantiations first.
note-14
The instantiation pattern (-, +, ?) is an extension to `standard' Prolog.
note-15
Upto version 3.2.x, atom_chars/2 behaved as the current atom_codes/2. The current definition is compliant with the ISO standard
note-16
This is also called atom_char/2 in older versions of SWI-Prolog as well as some other Prolog implementations. atom_char/2 is available from the library backcomp.pl
note-17
Please note that the semantics have changed between 3.1.1 and 3.1.2
note-18
Silent operation was the default upto version 3.2.6.
note-19
On Windows, the home directory is determined as follows: if the environment variable HOME exists, this is used. If the variables HOMEDRIVE and HOMEPATH exist (Windows-NT), these are used. At initialisation, the system will set the environment variable HOME to point to the SWI-Prolog home directory if neither HOME nor HOMEPATH and HOMEDRIVE are defined
note-20
BUG: Some of the file-I/O predicates use local filenames. Using chdir/1 while file-bound streams are open causes wrong results on telling/1, seeing/1 and current_stream/3
note-21
BUG: Erased clauses which could not actually be removed from the database, because they are active in the interpreter, will never be garbage collected after an abort.
note-22
A similar facility was added to Edinburgh C-Prolog by Wouter Jansweijer.
note-23
show_profile/1 is defined in Prolog and takes a considerable amount of memory.
note-24
This interface is contributed by Don Dwiggins.
note-25
BUG: I plan to supply a real gensym/2 which does give this warrant for future versions.
note-26
Although this would make it impossible to call B directly.
note-27
The system version uses recordz/2 and recorded/3.
note-28
The system also contains code to load .o files directly for some operating systems, notably Unix systems using the BSD a.out executable format. As the number of Unix platforms supporting this gets quickly smaller and this interface is difficult to port and slow, it is no longer described in this manual. The best alternatively would be to use the dld package on machines do not have shared libraries
note-29
Otherwise asynchronous atom garbage collection might detroy the atom before it is used.
note-30
Do not pass the integer 0 for normal operation, as this is interpreted as PL_Q_NODEBUG for backward compatibility reasons.
note-31
This interface differs in two ways from Quintus. The calling predicates simp,y signal failure if an exception was raised, and a term referenced is returned, rather passed and filled with the error term. Exceptions can only be handled using the PL_next_solution() interface, as a handle to the query is required
note-32
BUG: Various fatal errors may cause PL_initialise to call PL_halt(1), preventing it from returning at all.