ref-syn-syn-trm (SICStus Prolog)

`term-read-in`	::= `subterm(1200)` `full stop`

`subterm(N)`	::= `term(M)`	{ where `M` is less than or equal to `N` }

`term(N)`	::= `op(N,fx)` `subterm(N-1)`	{ except in the case of a `number` if `subterm` starts with a ‘`(`’, `op` must be followed by `whitespace-text` }
	\| `op(N,fy)` `subterm(N)`	{ if `subterm` starts with a ‘`(`’, `op` must be followed by `whitespace-text` }
	\| `subterm(N-1)` `op(N,xfx)` `subterm(N-1)`
	\| `subterm(N-1)` `op(N,xfy)` `subterm(N)`
	\| `subterm(N)` `op(N,yfx)` `subterm(N-1)`
	\| `subterm(N-1)` `op(N,xf)`
	\| `subterm(N)` `op(N,yf)`

`term(1100)`	::= `subterm(1099)` `\|` `subterm(1100)`	{ term with functor `;/2` unless `\|` is declared infix }
`term(1000)`	::= `subterm(999)` `,` `subterm(1000)`	{ term with functor `','/2` }

`term(0)`	::= `functor` `(` `arguments` `)`	{ provided there is no `whitespace-text` between the `functor` and the ‘`(`’ }
	\| `(` `subterm(1200)` `)`
	\| `{` `subterm(1200)` `}`
	\| `list`
	\| `string`
	\| `constant`
	\| `variable`

`op(N,T)`	::= `name`	{ where `name` has been declared as an operator of type `T` and precedence `N` }

`arguments`	::= `subterm(999)`
	\| `subterm(999)` `,` `arguments`

`list`	::= `[]`
	\| `[` `listexpr` `]`

`listexpr`	::= `subterm(999)`
	\| `subterm(999)` `,` `listexpr`
	\| `subterm(999)` `\|` `subterm(999)`

`constant`	::= `atom` \| `number`

`number`	::= `unsigned-number`
	\| `sign` `unsigned-number`

`unsigned-number`	::= `natural-number` \| `unsigned-float`

`atom`	::= `name`

`functor`	::= `name`