/*************************************************************************
* *
* YAP Prolog *
* *
* Yap Prolog was developed at NCCUP - Universidade do Porto *
* *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 2015- *
* *
**************************************************************************
* *
* File: YapGFlagInfo.h *
* Last rev: *
* mods: *
* comments: global flag enumeration. *
* *
*************************************************************************/
/** @file YapGFlagInfo.h
@addtogroup YAPFlags
@ingroup builtins
@{
@pred yap_flag( ?Param, ?Value)
Set or read system properties for _Param_:
@enum YapGFlag Prolog
@Brief global flag:
@enum GlobalFlags Global Flags Dupported ny YAP *
*/
YAP_FLAG(ADDRESS_BITS_FLAG, "address_bits", false, nat, BITNESS, NULL), /**< `address_bits`
Number of address bits in the machine, either 64 or 32 bits */
YAP_FLAG(AGC_MARGIN_FLAG, "agc_margin", true, nat, "10000",
agc_threshold), /**< `agc_margin`
An integer: if this amount of atoms has been created since the last
atom-garbage collection, perform atom garbage collection at the first
opportunity. Initial value is 10,000. May be changed. A value of 0
(zero) disables atom garbage collection.
*/
YAP_FLAG(ALLOW_ASSERT_FOR_STATIC_PREDICATES,
"allow_assert_for_static_predicates", true, booleanFlag, "true",
NULL), /**< `allow asserting and retracting clauses of static
predicates. */
/* YAP_FLAG( ALLOW_VARIABLE_NAME_AS_FUNCTOR_FLAG,
"allow_variable_name_as_functor", true, booleanFlag, "false" , NULL ),
/\**<
`allow_variable_name_as_functor` */
/* allow
* A(X)
* *\/
*/
YAP_FLAG(ANSWER_FORMAT_FLAG, "answer_format", true, isatom, "~p",
NULL), /** `arithmetic_exceptions `
Read-write flag telling whether arithmetic exceptions generate
Prolog exceptions. If enabled:
~~~~
?- X is 2/0.
ERROR!!
ZERO DIVISO]]R ERROR- X is Exp
~~~~
If disabled:
~~~~
?- X is 2/0.
X = (+inf).
~~~~
It is `true` by default, but it is disabled by packages like CLP(BN) and
ProbLog.
*/
#if __APPLE__
YAP_FLAG(APPLE_FLAG, "apple", false, booleanFlag, "true",
NULL), /**< `apple`
Read-only booleanFlag flag that unifies with `true` if YAP is
running on an Apple machine.
*/
#endif
YAP_FLAG(ARCH_FLAG, "arch", false, isatom, YAP_ARCH, NULL),
YAP_FLAG(ARGV_FLAG, "argv", false, argv, "@boot", NULL),
YAP_FLAG(ARITHMETIC_EXCEPTIONS_FLAG, "arithmetic_exceptions", true,
booleanFlag, "true", NULL),
YAP_FLAG(BACKQUOTED_STRING_FLAG, "backquoted_string", true, isatom,
"string", ), /**>
If _Value_ is unbound, tell whether a double quoted list of characters
token is converted to a list of atoms, `chars`, to a list of integers,
`codes`, or to a single atom, `atom`. If _Value_ is bound, set to
the corresponding behavior. The default value is `string`
*/
YAP_FLAG(BOUNDED_FLAG, "bounded", false, booleanFlag, "false",
NULL), /**< `bounded` is iso
Read-only flag telling whether integers are bounded. The value depends
on whether YAP uses the GMP library or not.
*/
YAP_FLAG(C_CC_FLAG, "c_cc", false, isatom, C_CC, NULL),
YAP_FLAG(C_CFLAGS_FLAG, "c_cflags", false, isatom, C_CFLAGS, NULL),
YAP_FLAG(C_LDFLAGS_FLAG, "c_ldflags", false, isatom, C_LDFLAGS, NULL),
YAP_FLAG(C_LIBPLSO_FLAG, "c_libplso", false, isatom, C_LIBPLSO, NULL),
YAP_FLAG(C_LIBS_FLAG, "c_libs", false, isatom, C_LIBS, NULL),
YAP_FLAG(CHAR_CONVERSION_FLAG, "char_conversion", true, booleanFlag,
"false", NULL), /**< `char_conversion is iso`
Writable flag telling whether a character conversion table is used when
reading terms. The default value for this flag is `off` except in
`sicstus` and `iso` language modes, where it is `on`.
*/
YAP_FLAG(CHARACTER_ESCAPES_FLAG, "character_escapes", true, booleanFlag,
"true", NULL), /**< `character_escapes is iso `
Writable flag telling whether a character escapes are enables,
`true`, or disabled, `false`. The default value for this flag is
`true`. */
YAP_FLAG(COLON_SETS_CALLING_CONTEXT_FLAG, "colon_sets_calling_context",
true, booleanFlag, "true", NULL),
YAP_FLAG(COMPILED_AT_FLAG, "compiled_at", false, isatom, YAP_COMPILED_AT,
NULL), /**< `compiled_at `
Read-only flag that gives the time when the main YAP binary was compiled. It is
obtained staight from the __TIME__ macro, as defined in the C99.
*/
YAP_FLAG(DEBUG_FLAG, "debug", true, booleanFlag, "false",
NULL), /**< `debug is iso `
If _Value_ is unbound, tell whether debugging is `true` or
`false`. If _Value_ is bound to `true` enable debugging, and if
it is bound to `false` disable debugging.
*/
YAP_FLAG(DEBUG_INFO_FLAG, "debug_info", true, booleanFlag, "true", NULL),
YAP_FLAG(DEBUG_ON_ERROR_FLAG, "debug_on_error", true, booleanFlag, "true",
NULL),
YAP_FLAG(DEBUGGER_PRINT_OPTIONS_FLAG, "debugger_print_options", true,
list_option,
"[quoted(true),numbervars(true),portrayed(true),max_depth(10)]",
NULL), /**< `debugger_print_options `
If bound, set the argument to the `write_term/3` options the
debugger uses to write terms. If unbound, show the current options.
*/
YAP_FLAG(DEBUGGER_SHOW_CONTEXT_FLAG, "debugger_show_context", true,
booleanFlag, "false", NULL),
YAP_FLAG(DIALECT_FLAG, "dialect", false, ro, "yap",
NULL), /**< `dialect `
Read-only flag that always returns `yap`.
*/
YAP_FLAG(DISCONTIGUOUS_WARNINGS_FLAG, "discontiguous_warnings", true,
booleanFlag, "true", NULL), /**< `discontiguous_warnings `
If `true` (default `true`) YAP checks for definitions of the same predicate that
are separated by clauses for other predicates. This may indicate that different
procedures have the same name.
The declaration discontiguous/1 disables this warning for user-specified
predicates.
*/
YAP_FLAG(DOLLAR_AS_LOWER_CASE_FLAG, "dollar_as_lower_case", true,
booleanFlag, "false",
NULL), /**< `dollar_as_lower_case `
If `off` (default) consider the character `$` a control character, if
`on` consider `$` a lower case character.
*/
YAP_FLAG(DOUBLE_QUOTES_FLAG, "double_quotes", true, isatom, "codes",
dqf), /**< `double_quotes is iso `
If _Value_ is unbound, tell whether a double quoted list of characters
token is converted to a list of atoms, `chars`, to a list of integers,
`codes`, or to a single atom, `atom`. If _Value_ is bound, set to
the corresponding behavior. The default value is `codes`. */
YAP_FLAG(EDITOR_FLAG, "editor", true, isatom, "$EDITOR", NULL),
YAP_FLAG(EXECUTABLE_FLAG, "executable", false, executable, "@boot",
NULL), /**< `executable `
Read-only flag. It unifies with an atom that gives the
original program path.
*/
YAP_FLAG(FAST_FLAG, "fast", true, booleanFlag, "false", NULL), /**< `fast `
If `on` allow fast machine code, if `off` (default) disable it. Only
available in experimental implementations.
*/
YAP_FLAG(FILE_NAME_VARIABLES_FLAG, "file_name_variables", true, booleanFlag,
"true", NULL),
YAP_FLAG(FLOAT_FORMAT_FLAG, "float_format", true, isatom, "%.16g",
NULL), /**< + `float_format `
C-library `printf()` format specification used by write/1 and
friends to determine how floating point numbers are printed. The
default is `%.15g`. The specified value is passed to `printf()`
without further checking. For example, if you want less digits
printed, `%g` will print all floats using 6 digits instead of the
default 15.
*/
YAP_FLAG(GC_FLAG, "gc", true, booleanFlag, "on", NULL), /**< `gc`
If `on` allow garbage collection (default), if `off` disable it.
*/
YAP_FLAG(GC_MARGIN_FLAG, "gc_margin", true, nat, "0",
gc_margin), /**< `gc_margin `
Set or show the minimum free stack before starting garbage
collection. The default depends on total stack size.
*/
YAP_FLAG(GC_TRACE_FLAG, "gc_trace", true, isatom, "off",
NULL), /**< `gc_trace `
If `off` (default) do not show information on garbage collection
and stack shifts, if `on` inform when a garbage collection or stack
shift happened, if verbose give detailed information on garbage
collection and stack shifts. Last, if `very_verbose` give detailed
information on data-structures found during the garbage collection
process, namely, on choice-points.
*/
YAP_FLAG(GENERATE_DEBUGGING_INFO_FLAG, "generate_debug_info", true,
booleanFlag, "true", NULL), /**< `generate_debug_info `
If `true` (default) generate debugging information for
procedures, including source mode. If `false` predicates no
information is generated, although debugging is still possible, and
source mode is disabled.
*/
YAP_FLAG(GMP_VERSION_FLAG, "gmp_version", false, isatom, "4.8.12", NULL),
YAP_FLAG(HALT_AFTER_CONSULT_FLAG, "halt_after_consult", false, booleanFlag,
"false", NULL),
YAP_FLAG(HOME_FLAG, "home", false, isatom, YAP_ROOTDIR, NULL), /**< home `
the root of the YAP installation, by default `/usr/local` in Unix or
`c:\Yap` in Windows system. Can only be set at configure time
*/
YAP_FLAG(HOST_TYPE_FLAG, "host_type", false, isatom, HOST_ALIAS,
NULL), /**< host_type `
Return `configure` system information, including the machine-id
for which YAP was compiled and Operating System information.
*/
YAP_FLAG(INDEX_FLAG, "index", true, indexer, "multi", NULL), /**< `index `
If `on` allow indexing (default), if `off` disable it, if
`single` allow on first argument only.
*/
YAP_FLAG(INDEX_SUB_TERM_SEARCH_DEPTH_FLAG, "index_sub_term_search_depth",
true, nat, "0", NULL), /**< `Index_sub_term_search_depth `
Maximum bound on searching sub-terms for indexing, if `0` (default) no bound.
*/
YAP_FLAG(INFORMATIONAL_MESSAGES_FLAG, "informational_messages", true,
isatom, "normal", NULL), /**< `informational_messages `
If `on` allow printing of informational messages, such as the ones
that are printed when consulting. If `off` disable printing
these messages. It is `on` by default except if YAP is booted with
the `-L` flag.
*/
YAP_FLAG(INTEGER_ROUNDING_FUNCTION_FLAG, "integer_rounding_function", true,
isatom, "toward_zero",
NULL), /**< `integer_rounding_function is iso `
Read-only flag telling the rounding function used for integers. Takes the value
`toward_zero` for the current version of YAP.
*/
YAP_FLAG(ISO_FLAG, "iso", true, booleanFlag, "false", NULL),
YAP_FLAG(LANGUAGE_FLAG, "language", true, isatom, "yap",
NULL), /**< `language `
Choose whether YAP follows native, closer to C-Prolog, `yap`, iso-prolog,
`iso` or SICStus Prolog, `sicstus`. The current default is
`cprolog`. This flag affects update semantics, leashing mode,
style checking, handling calls to undefined procedures, how directives
are interpreted, when to use dynamic, character escapes, and how files
are consulted. Also check the `dialect` option.
*/
YAP_FLAG(PROLOG_LIBRARY_DIRECTORY_FLAG, "prolog_library_directory", true, isatom, "", NULL), /**< if defined, first location where YAP expects to find the YAP Prolog library. Takes precedence over library_directory */
YAP_FLAG(PROLOG_FOREIGN_DIRECTORY_FLAG, "prolog_foreign_directory", true, isatom, "", NULL), /**< if defined, first location where YAP expects to find the YAP Prolog shared libraries (DLLS). Takes precedence over executable_directory/2. */
YAP_FLAG(MAX_ARITY_FLAG, "max_arity", false, isatom, "unbounded",
NULL), /**< `max_arity is iso `
Read-only flag telling the maximum arity of a functor. Takes the value
`unbounded` for the current version of YAP.
*/
YAP_FLAG(MAX_TAGGED_INTEGER_FLAG, "max_tagged_integer", false, at2n,
"INT_MAX", NULL),
YAP_FLAG(MAX_THREADS_FLAG, "max_threads", false, at2n, "MAX_THREADS", NULL),
YAP_FLAG(MAX_WORKERS_FLAG, "max_workers", false, at2n, "MAX_WORKERS", NULL),
YAP_FLAG(MIN_TAGGED_INTEGER_FLAG, "min_tagged_integer", false, at2n,
"INT_MIN", NULL),
YAP_FLAG(N_OF_INTEGER_KEYS_IN_DB_FLAG, "n_of_integer_keys_in_db", false, ro,
"256", NULL),
YAP_FLAG(OCCURS_CHECK_FLAG, "occurs_check", true, booleanFlag, "false",
NULL),
YAP_FLAG(OPEN_EXPANDS_FILENAME_FLAG, "open_expands_filename", true,
booleanFlag, "false", NULL), /**< `open_expands_filename `
If `true` the open/3 builtin performs filename-expansion
before opening a file (SICStus Prolog like). If `false` it does not
(SWI-Prolog like).
*/
YAP_FLAG(OPEN_SHARED_OBJECT_FLAG, "open_shared_object", true, booleanFlag,
"true", NULL), /**< `open_shared_object `
If true, `open_shared_object/2` and friends are implemented,
providing access to shared libraries (`.so` files) or to dynamic link
libraries (`.DLL` files).
*/
// YAP_FLAG(MODULE_INDEPENDENT_OPERATORS_FLAG,
// "module_independent_operators", true, booleanFlag,
// "false", NULL),
/**< `module_independent_operators `
If `true` an operator declaration will be valid for every module in the
program. This is for compatibility with old software that
might expect module-independent operators.
*/
YAP_FLAG(OPTIMISE_FLAG, "optimise", true, booleanFlag, "false", NULL),
YAP_FLAG(OS_ARGV_FLAG, "os_argv", false, os_argv, "@boot", NULL),
YAP_FLAG(PID_FLAG, "pid", false, sys_pid, "@boot", NULL),
YAP_FLAG(PIPE_FLAG, "pipe", true, booleanFlag, "true", NULL),
YAP_FLAG(PROFILING_FLAG, "profiling", true, booleanFlag, "false",
NULL), /**< `profiling `
If `off` (default) do not compile call counting information for
procedures. If `on` compile predicates so that they calls and
retries to the predicate may be counted. Profiling data can be read through the
call_count_data/3 built-in.
*/
YAP_FLAG(PROMPT_ALTERNATIVES_ON_FLAG, "prompt_alternatives_on", true,
isatom, "determinism", NULL), /**< `prompt_alternatives_on(atom,
changeable) `
SWI-Compatible option, determines prompting for alternatives in the Prolog
toplevel. Default is groundness, YAP prompts for alternatives if and
only if the query contains variables. The alternative, default in SWI-Prolog is
determinism which implies the system prompts for alternatives if the
goal succeeded while leaving choicepoints. */
YAP_FLAG(QUASI_QUOTATIONS_FLAG, "quasi_quotations", true, booleanFlag,
"true", NULL),
YAP_FLAG(READLINE_FLAG, "readline", true, booleanFlag, "false",
Yap_InitReadline), /**< `readline(boolean, changeable)`
}
enable the use of the readline library for console interactions, true by default
if readline was found. */
YAP_FLAG(REPORT_ERROR_FLAG, "report_error", true, booleanFlag, "true",
NULL),
YAP_FLAG(RESOURCE_DATABASE_FLAG, "resource_database", false, isatom,
"boot.yap", NULL),
/**<`resource_database`
Name of the resource file (saved-state or Prolog file) used to construct
the YAP
run-time environment.
*/
YAP_FLAG(SAVED_PROGRAM_FLAG, "saved_program", false, booleanFlag, "false",
NULL),
/**<`saved_program`
if `true` YAP booted from a `yss` file, usually `startup.yss'. If
`false`, YAP booted from a Prolog file, by default `boot.yap`.
*/
YAP_FLAG(SHARED_OBJECT_EXTENSION_FLAG, "shared_object_extension", false,
isatom, SO_EXT, NULL), /**< `shared_object_extension `
Suffix associated with loadable code.
*/
YAP_FLAG(SHARED_OBJECT_SEARCH_PATH_FLAG, "shared_object_search_path", true,
isatom, SO_PATH, NULL), /**< `shared_object_search_path `
Name of the environment variable used by the system to search for shared
objects.
*/
YAP_FLAG(SIGNALS_FLAG, "signals", true, booleanFlag, "true",
NULL), /**< `signals`
If `true` (default) YAP handles Signals such as `^C`
(`SIGINT`).
*/
YAP_FLAG(SOURCE_FLAG, "source", true, booleanFlag, "true",
NULL), /**< `source`
If `true` maintain the source for all clauses. Notice that this is trivially
supported for facts, and always supported for dynamic code.
*/
YAP_FLAG(STRICT_ISO_FLAG, "strict_iso", true, booleanFlag, "false",
NULL), /**< `strict_iso `
If _Value_ is unbound, tell whether strict ISO compatibility mode
is `on` or `off`. If _Value_ is bound to `on` set
language mode to `iso` and enable strict mode. If _Value_ is
bound to `off` disable strict mode, and keep the current language
mode. The default for YAP is `off`.
Under strict ISO Prolog mode all calls to non-ISO built-ins generate an
error. Compilation of clauses that would call non-ISO built-ins will
also generate errors. Pre-processing for grammar rules is also
disabled. Module expansion is still performed.
Arguably, ISO Prolog does not provide all the functionality required
from a modern Prolog system. Moreover, because most Prolog
implementations do not fully implement the standard and because the
standard itself gives the implementor latitude in a few important
questions, such as the unification algorithm and maximum size for
numbers there is no guarantee that programs compliant with this mode
will work the same way in every Prolog and in every platform. We thus
believe this mode is mostly useful when investigating how a program
depends on a Prolog's platform specific features.
*/
YAP_FLAG(SYSTEM_OPTIONS_FLAG, "system_options", false, options,
SYSTEM_OPTIONS,
NULL), /**< `system_options `
This read only flag tells which options were used to compile
YAP. Currently it informs whether the system supports `big_numbers`,
`coroutining`, `depth_limit`, `low_level_tracer`,
`or-parallelism`, `rational_trees`, `readline`, `tabling`,
`threads`, or the `wam_profiler`.
*/
YAP_FLAG(SYSTEM_THREAD_ID_FLAG, "system_thread_id", false, sys_thread_id,
"@boot", NULL),
YAP_FLAG(TABLING_MODE_FLAG, "tabling_mode", true, isatom, "[]",
NULL), /**< `tabling_mode`
Sets or reads the tabling mode for all tabled predicates. Please
(see Tabling) for the list of options.
*/
YAP_FLAG(THREADS_FLAG, "threads", false, ro, "MAX_THREADS", NULL),
YAP_FLAG(TIMEZONE_FLAG, "timezone", false, ro, "18000", NULL),
YAP_FLAG(TOPLEVEL_PRINT_ANON_FLAG, "toplevel_print_anon", true, booleanFlag,
"true", NULL),
YAP_FLAG(TOPLEVEL_PRINT_OPTIONS_FLAG, "toplevel_print_options", true,
list_option, "[quoted(true),numbervars(true),portrayed(true)]",
NULL), /**< `toplevel_hook `
If bound, set the argument to a goal to be executed before entering the
top-level. If unbound show the current goal or `true` if none is
presented. Only the first solution is considered and the goal is not
backtracked into.
*/
YAP_FLAG(TOPLEVEL_PROMPT_FLAG, "toplevel_prompt", true, isatom, "?- ",
mkprompt),
YAP_FLAG(TTY_CONTROL_FLAG, "tty_control", true, booleanFlag, "true", NULL),
YAP_FLAG(UNIX_FLAG, "unix", false, ro, "true", NULL), /**< `unix`
Read-only BooleanFlag flag that unifies with `true` if YAP is
running on an Unix system. Defined if the C-compiler used to compile
this version of YAP either defines `__unix__` or `unix`.
*/
YAP_FLAG(UPDATE_SEMANTICS_FLAG, "update_semantics", true, isatom, "logical",
NULL), /**< `update_semantics `
Define whether YAP should follow `immediate` update
semantics, as in C-Prolog (default), `logical` update semantics,
as in Quintus Prolog, SICStus Prolog, or in the ISO standard. There is
also an intermediate mode, `logical_assert`, where dynamic
procedures follow logical semantics but the internal data base still
follows immediate semantics.
*/
YAP_FLAG(USER_FLAGS_FLAG, "user_flags", true, isatom, "error", NULL), /**<
`user_flags `
Define the behaviour of set_prolog_flag/2 if the flag is not known. Values
are `silent`, `warning` and `error`. The first two create the flag
on-the-fly, with `warning` printing a message. The value `error` is
consistent with ISO: it raises an existence error and does not create the
flag. See also `create_prolog_flag/3`. The default is`error`, and developers
are encouraged to use `create_prolog_flag/3` to create flags for their
library.
*/
YAP_FLAG(UNKNOWN_FLAG, "unknown", true, isatom, "error",
Yap_unknown), /**< `unknown is iso`
Corresponds to calling the unknown/2 built-in. Possible ISO values
are `error`, `fail`, and `warning`. Yap includes the following extensions:
`fast_fail` does not invoke any handler.
*/
YAP_FLAG(VARIABLE_NAMES_MAY_END_WITH_QUOTES_FLAG,
"variable_names_may_end_with_quotes", true, booleanFlag, "false",
NULL),
YAP_FLAG(VERBOSE_FLAG, "verbose", true, isatom, "normal",
NULL), /**< `verbose `
If `normal` allow printing of informational and banner messages,
such as the ones that are printed when consulting. If `silent`
disable printing these messages. It is `normal` by default except if
YAP is booted with the `-q` or `-L` flag.
*/
YAP_FLAG(VERBOSE_AUTOLOAD_FLAG, "verbose_autoload", true, booleanFlag,
"false", NULL),
YAP_FLAG(VERBOSE_FILE_SEARCH_FLAG, "verbose_file_search", true, booleanFlag,
"false", NULL), /**< `verbose_file_search `
If `true` allow printing of informational messages when
searching for file names. If `false` disable printing these messages. It
is `false` by default except if YAP is booted with the `-L`
flag.
*/
YAP_FLAG(VERBOSE_LOAD_FLAG, "verbose_load", true, isatom, "normal",
NULL), /**< `verbose_load `
If `true` allow printing of informational messages when
consulting files. If `false` disable printing these messages. It
is `normal` by default except if YAP is booted with the `-L`
flag.
*/
YAP_FLAG(VERSION_FLAG, "version", false, nat, YAP_NUMERIC_VERSION,
NULL), /**< `version_data `
Read-only flag that unifies with a number of the form
`_Major_ * 100000 + _Minor_ *100 + _Patch_`, where
_Major_ is the major version, _Minor_ is the minor version,
and _Patch_ is the patch number.
*/
YAP_FLAG(VERSION_DATA_FLAG, "version_data", false, ro, YAP_TVERSION,
NULL), /**<
`version ` Read-only flag that returns a compound term with the
current version of YAP. The term will have the name `yap` and arity 4, the first
argument will be the
major version, the second the minor version, the third the patch number, and the
last one is reserved.
*/
YAP_FLAG(VERSION_GIT_FLAG, "version_git", false, isatom, YAP_GIT_HEAD,
NULL), /**< `version_git `
`
this is the unique identifier for the last commit of the current GIT HEAD, it
xan be used to identify versions that differ on small (or large) updates.
*/
YAP_FLAG(WRITE_ATTRIBUTES_FLAG, "write_attributes", true, isatom, "ignore",
NULL),
#if __WINDOWS__
YAP_FLAG(WINDOWS_FLAG, "windows", false, ro, "true", NULL), /**< `windows `
Read-only booleanFlag flag that unifies with `true` if YAP is
running on an Windows machine.
*/
#endif
YAP_FLAG(WRITE_STRINGS_FLAG, "write_strings", true, booleanFlag, "false",
NULL), /**< `write_strings `
Writable flag telling whether the system should write lists of
integers that are writable character codes using the list notation. It
is `on` if enables or `off` if disabled. The default value for
this flag is `off`.
*/
//! @}