Yes.
Of course. Numbers can serve as reference symbols. Subtitles can also refer to specific parts or symbologies such as the A-A section. Sometimes a combination of numbers and letters can be used as reference marks.
In modern times, a patent is generally a document issued upon application by a government agency or a regional organization representing several countries. This document records the content of the invention and creation, and is produced within a certain period of time. A legal state in which a patented invention can generally be implemented by others only with the permission of the patentee. In my country, patents are divided into three types: invention, utility model and design.