The full syntax (not including the optional use of standard brackets to define precedence) is described using Backus-Naur Formalism:
set_expression ::= { set_entity { set_operator set_entity } }
set_entity ::= set_identifier [ set_modifier ] | set_modifier
set_identifier ::= 1 | $ | $N | $_N | bookmark_id | bookmark_name
set_operator ::= + | - | * | /
set_modifier ::= < field_selection {, field_selection } >
field_selection ::= field_name [ = | += | –= | *= | /= ] element_set_expression
element_set_expression ::= [ - ] element_set { set_operator element_set }
element_set ::= [ field_name ] | { element_list } | element_function
element_list ::= element { , element }
element_function ::= ( P | E ) ( [set_expression] [field_name] )
element ::= field_value | " search_mask "