Information Classification for Client SOP

Currently our organization's information classification is: confidential, private & confidential, internal and unclassified. We are in the process of reviewing our classification and we found that there is a document that can be classified into one of classification. This document is some kind of SOP that we provide for our clients. We would like to know what this document should be classified as? This document is not confidential but we concern about copyrights and plagiarism issue if this document is not properly classified.