`atom(`

`+T``)`

ISO- term
`T`is an atom `atomic(`

`+T``)`

ISO- term
`T`is an atom or a number `callable(`

`+T``)`

`T`is an atom or a compound term`compound(`

`+T``)`

ISO`T`is a compound term`db_reference(`

`+X``)`

**since release 4.1**`X`is a db_reference`float(`

`+N``)`

ISO`N`is a floating-point number`ground(`

`+T``)`

- term
`T`is a nonvar, and all substructures are nonvar `integer(`

`+T``)`

ISO- term
`T`is an integer `mutable(`

`+X``)`

`X`is a mutable term`nonvar(`

`+T``)`

ISO- term
`T`is one of atom, number, compound (that is,`T`is instantiated) `number(`

`+N``)`

ISO`N`is an integer or a float`simple(`

`+T``)`

`T`is not a compound term; it is either atomic or a var`var(`

`+T``)`

ISO- term
`T`is a variable (that is,`T`is uninstantiated)

`compare(`

`-C``,`

`+X``,`

`+Y``)`

- C is the result of comparing terms
`X`and`Y` `+X``==`

`+Y`- terms
`X`and`Y`are strictly identical `+X``\==`

`+Y`- terms
`X`and`Y`are not strictly identical `+X``@<`

`+Y`- term
`X`precedes term`Y`in standard order for terms `+X``@>=`

`+Y`- term
`X`follows or is identical to term`Y`in standard order for terms `+X``@>`

`+Y`- term
`X`follows term`Y`in standard order for terms `+X``@=<`

`+Y`- term
`X`precedes or is identical to term`Y`in standard order for terms

`?T``=..`

`?L`- the functor and arguments of term
`T`comprise the list`L` `?X``=`

`?Y`- terms
`X`and`Y`are unified `+X``\=`

`+Y`- terms
`X`and`Y`no not unify `?=(`

`+X``,`

`+Y``)`

`X`and`Y`are either strictly identical or don't unify`acyclic_term(`

`+T``)`

**since release 4.3, ISO**- term
`T`is a finite (acyclic) term `arg(`

`+N``,`

`+T``,`

`-A``)`

ISO- the
`N`th argument of term`T`is`A` `atom_chars(`

`?A``,`

`?L``)`

ISO`A`is the atom containing the character atoms in list`L``atom_codes(`

`?A``,`

`?L``)`

ISO`A`is the atom containing the characters in code-list`L``atom_concat(`

`?Atom1``,`

`?Atom2``,`

`?Atom12``)`

ISO- Atom
`Atom1`concatenated with`Atom2`gives`Atom12`. `atom_length(`

`+Atom``,`

`-Length``)`

ISO`Length`is the number of characters of the atom`Atom`.`char_code(`

`?Char``,`

`?Code``)`

ISO`Code`is the character code of the one-char atom`Char`.`copy_term(`

`+T``,`

`-C``)`

ISO`C`is a copy of`T`in which all variables have been replaced by new variables`copy_term(`

`+T``,`

`-C``,`

`-G``)`

`C`is a copy of`T`in which all variables have been replaced by new variables, and`G`is a goal for reinstating any attributes in`C``create_mutable(`

`+Datum``,`

`-Mutable``)`

`Mutable`is a new mutable term with current value`Datum`.`dif(`

`+X``,`

`+Y``)`

`X`and`Y`are constrained to be different.`frozen(`

`+Var``,`

`-Goal``)`

- The goal
`Goal`is blocked on the variable`Var`. `functor(`

`?T``,`

`?F``,`

`?N``)`

ISO- the principal functor of term
`T`has name`F`and arity`N` `get_mutable(`

`-Datum``,`

`+Mutable``)`

- The current value of the mutable term
`Mutable`is`Datum`. `name(`

`?A``,`

`?L``)`

- the code-list of atom or number
`A`is`L` `number_chars(`

`?N``,`

`?L``)`

ISO`N`is the numeric representation of list of character atoms`L``number_codes(`

`?N``,`

`?L``)`

ISO`N`is the numeric representation of code-list`L``numbervars(`

`+T``,`

`+M``,`

`-N``)`

- number the variables in term
`T`from`M`to`N`-1 `sub_atom(`

`+Atom``,`

`?Before``,`

`?Length``,`

`?After``,`

`?SubAtom``)`

ISO- The characters of
`SubAtom`form a sublist of the characters of`Atom`, such that the number of characters preceding`SubAtom`is`Before`, the number of characters after`SubAtom`is`After`, and the length of`SubAtom`is`Length`. `subsumes_term(General,Specific)`

**since release 4.3, ISO**`Specific`is an instance of`General``term_variables(`

`+Term``,`

`-Variables``)`

**since release 4.3, ISO**`Variables`is the set of variables that occur in`Term``unify_with_occurs_check(`

`?X``,`

`?Y``)`

ISO- True if
`X`and`Y`unify to a finite (acyclic) term.

`?T``=..`

`?L`- the functor and arguments of term
`T`comprise the list`L` `append(`

`?A``,`

`?B``,`

`?C``)`

- the list
`C`is the concatenation of lists`A`and`B` `keysort(`

`+L``,`

`-S``)`

- the list
`L`sorted by key yields`S` `length(`

`?L``,`

`?N``)`

- the length of list
`L`is`N` `member(`

`?X``,`

`?L``)`

`X`is a member of`L``memberchk(`

`+X``,`

`+L``)`

`X`is a member of`L``nonmember(`

`+X``,`

`+L``)`

`X`is not a member of`L``sort(`

`+L``,`

`-S``)`

- sorting the list
`L`into order yields`S`

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