Sometimes, establishments look for an ID number in order as another measure of confirming that the holder is indeed the person specified in the letter.
You have to write authorization letters with various intentions and for various responsibilities. Write their full name.
For instance, you may be sending a recommendation letter, cover letter or any other job application material to someone you don't know. Authorization letters can be written for quite a number of reasons, but the most common ones include authorization of power of attorney, confirmation to proceed with a project, authorization to collect documents, parental authorization for a child to travel, and authorization to act on behalf of someone.
This may happen many times during your job search. Authorization letters are required for the documentation of the offices and so you must not beat around the bush in the authorization letters.
Just replace the highlighted texts with your own information. Contact number of the requester. But you can add your landline and email too, for good measure. The requester is the one who is asking for a favor and who signs the letter.