How to sign an electronic document?

Question

Document flow

How to sign an electronic document? Of course, from a technical point of view.
Do you need to take only the text, without formatting, or the entire document container (with all styles, etc.) and apply the hashing function, according to the algorithm specified in the organization?
For example, there is an html page with information, there is a docx and there is a pdf - different hash function algorithms can be applied to each type of document.

Answer 1

Usually the document itself, sometimes there is only text, but here it is necessary to accurately indicate the beginning and end. The rules are set in the document management system itself.

Answer 2

in addition to hashing, you also need the signature itself with a private key, as well as the message container in which it will be packed. and of course, all this, starting with hashing, is determined by certain standards, otherwise who will parse and verify your signature