TSG DSL: What is the purpose of periods?

[ghost]

What is the purpose of the period character in these examples?

; Example 1
(import_from_statement
    module_name: (dotted_name (_) @left . (_) @right)
) ; ...

; Example 2
(import_from_statement
    module_name: (dotted_name (_) @last_name .)
    name: (_) @name
) ; ...

[ghost]

Oh! nevermind. It's the anchor operator of tree-sitter DSL
https://tree-sitter.github.io/tree-sitter/using-parsers#query-syntax