Iāve no idea of the level of confidentiality of the document. A watermark doesnāt really tell anything without context and further detailed info. So your use of the word āconfidentialā really isnāt all that useful either.
You also didnāt use correct punctuation and Iād prefer if you used capital letters at the start of your sentences.
Just to help you out a bit hereās information from the official secrets act
āofficial informationā means any secret official code word or password, and any sketch, plan, model, article, note, document or information which is secret or confidential or is expressed to be either and which is or has been in the possession, custody or control of a holder of a public office, or to which he has or had access, by virtue of his office, and includes information recorded by film or magnetic tape or by any other recording medium