集合的语法

完整语法(不包括选用标准括号定义优先级)使用 Backus-Naur 形式进行介绍:

set_expression ::= { set_entity { set_operator set_entity } }

set_entity ::= set_identifier [ 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 "