a superscript
In MLA style, the superscript number is used as a note reference mark to signal the existence of an explanatory note. The superscript number corresponds to the note located at the bottom of the page or end of the document.
Note Reference Marks
Yes
footnote
it is a header
Yes
Yes. The requirement to signal always exists.
A "signal plan" is typically a document that outlines how signals are used or managed, whether in traffic control or communication systems. It specifies signal timings in traffic or signal allocation in communication networks.
Yes.
Physical layer which is the first layer in OSI reference model is responsible for signal encoding and decoding.
Many types of signal exists.
remove steering wheel and then it's pretty self explanatory.