Information provided by Juan Carlos Ayala in personal correspondence to John Griffiths, 6 February, 2006: (translated JG) “In 1999, during the research carried out towards his thesis, the professor of music, Carlos Messa Poullet, discovered a fragment of tablature for a six-course instrument in one of the baptismal register books of the Parish of the Sagrario in Málaga. The book in question contains the baptisms of that parish from 1556 to 1570.”
• Thesis title: MESSA POULLET, Carlos. "La música vocal en Málaga en el siglo XVI" (Málaga, 1999).
• Document: Archivo Diocesano de Málaga, "Libro de Bautismos de la Santa Yglesia Catedral de Málaga" Años 1.558-1.570. Fol. 81, verso
The commentary on the fragment from the thesis reads as follows (page number unknown)
“La tablatura, de tipo italiano, cuenta con tan sólo seis compases, de los cuales los dos primeros están tachados e incompletos. Llama la atención la cuidadísima caligrafía si lo comparamos con otros manuscritos para vihuela como el de Simancas o el que se encuentra en el ejemplar de los "Tres Libros de Música en Cifra para Vihuela" de Alonso de Mudarra conservado en la Biblioteca Nacional. El tipo de grafía se asemeja considerablemente a las tablaturas impresas de Luys de Narváez (1536) o Alonso de Mudarra (1546).
“Otro aspecto que llama la atención es la presencia de claves. El uso de claves es poco habitual en las tablaturas impresas de vihuela, y es inexistente en los pocos manuscritos de música destinada a este instrumento que se conservan. Tan sólo Luys de Narváez hace uso de claves en su libro de música para vihuela....
“La música contenida en la tablatura no ha sido identificada, dada su brevedad. Comienza con un acorde de cinco notas que se repite tres veces para pasar al cuarto grado, lo que coincide con el patrón armónico de Conde Claros, una de las piezas favoritas de los vihuelistas para desarrollar sus series de diferencias…
“La presencia del fragmento de tablatura en un libro de bautismos hace pensar que el autor pertenecía a la Parroquia del Sagrario o a la Catedral, alguien con acceso al libro de bautismos, el párroco o el sacristán de la Parroquia muy probablemente.

The fragment is undoubtedly for vihuela (or lute). The date is impossible to discern from the writing, but I would say it must be after 1540. The copyist has written it very carefully despite the deletion in the first bar. The clefs at the beginning show a similar use to that of Narváez to indicate the tuning of the vihuela, but he made a mistake with the F clef that should be on the fourth line. There is also no logical explanation for the absence of a rhythmic sign in the first bars. The writing of the rest shows a hand trying to emulate the shape of the types in the print, for example the use of the Z shape for the 2, and the dots to align the rhythmic symbols with the numbers.
The "work" must be the beginning of an intabulation. There are several possible interpretations. The most reasonable - but not the only possible - is that the work begins where the rhythmic indication begins. The first two bars can be frustrated attempts to clearly indicate the first chord. In the last measure he began to place the chord (from F) in third position (perhaps coding from the bass upwards) after realizing that one of the common positions of the instrument served him. At this point he realised - possibly - that coding directly from the parts was going to be problematic and perhaps decided to put the vocal polyphony on the score before he started coding. -- Maybe I'm going too far, but it's a possible scenario.