When doing so is useful to readers, specialists often supply missing publication dates, using a range of methods. For example, a medievalist with expertise in paleography might date a manuscript by looking at its handwriting. If there is a compelling reason to supply a missing date of publication by looking at source code, a specialist researcher can follow the guidelines in the MLA Handbook, section 2.6.1, and use brackets and a question mark to indicate that the information is supplied by the specialist and not certain.