Parentheses and operator precedence

In general an expression may be enclosed in parentheses without changing its meaning.

If parentheses are not used, operator precedence follows the sequence below, starting with the operators that bind most tightly. Within each group the operators are evaluated left-to-right

Operator	Meaning
`[]`, `()`	predicate, function call
`/`, `//`	path operator
`!`	simple mapping operator (XPath 3.0)
unary `-`, unary `+`	unary plus and minus
`cast as`	dynamic type conversion
`castable as`	type test
`treat as`	static type conversion
`instance of`	type test
`except`, `intersect`	set difference and intersection
`\|`, `union`	union operation on sets
`*`, `div`, `idiv`, `mod`	multiply, divide, integer divide, modulo
`+`, `-`	plus, minus
`to`	range expression
`\|\|`	string concatenation (XPath 3.0)
`=`, `!=`, `is`, `<`, `<=;`, `>`, `>=`, `eq`, `ne`, `lt`, `le`, `gt`, `ge`	comparisons
`and`	Boolean and
`or`	Boolean or
`if`	conditional expressions
`some`, `every`	quantified expressions
`for`	iteration (mapping) over a sequence
`,` (comma)	Sequence concatenation

The various operators are described, in roughly the above order, in the sections that follow.