`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``)`

`X`is currently instantiated to 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 currently instantiated to 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)

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