The coding of persons in catalog records of dissertations can be interpreted as putting forward different implicit theories about who wrote these texts. Two pairings follow the model of the ‘sole author’, since neither dedicatees nor printers are involved in the production of the original text. The most common solution contrasts an ‘author’, presumably the <hi xmlns="http://www.tei-c.org/ns/1.0" rend="italic">respondens</hi>, and the ‘thesis advisor’, mirroring the role of the <hi xmlns="http://www.tei-c.org/ns/1.0" rend="italic">praeses</hi>, with the one significant difference that modern advisors might not write the thesis they supervise themselves. Some librarians espouse the model of ‘co-authorship’, naming both contributors as authors. Others contrast an ‘author’ and an ‘opponent’, asserting implicitly the authorship of the <hi xmlns="http://www.tei-c.org/ns/1.0" rend="italic">praeses</hi>. Finally, a <hi xmlns="http://www.tei-c.org/ns/1.0" rend="italic">praeses</hi> (or a <hi xmlns="http://www.tei-c.org/ns/1.0" rend="italic">respondens</hi>?) is taken to be an editor of a text prepared by an author. The use of the code ‘0’ or ‘60’ indicates neutrality or lack of verifiable knowledge with regard to the exact contribution of each named person.