The modest collection of manuscripts of guitar music preserved in the Senate Library of Madrid seems to provide a representative sampling of the types of guitar repertoire circulating in Spain in the late eighteenth and early nineteenth centuries. Despite its small size, this corpus contains the most typical genres of the period— namely, two chamber music works for guitar with bowed string instruments, by Federico Moretti and Antonio Ximénez, a guitar duet by Pierre-Jean Porro, a solo guitar work by the mysterious señor D. G. G. M. A., and two songs with guitar accompaniment, one by Francisco Xavier Moreno and the other by the same D. G. G. M. A., titled Canción patriótica de la Alianza. Among other interesting aspects, what is truly remarkable about this song is that its author uses two G-clef staves in the introduction to write the music of a single guitar, a surprising notational device also used in another of his pieces.
Aleixo, Ricardo. 2017. "Guitar Music Manuscripts in the Senate Library of Madrid: The Canción patriótica de la Alianza and Its Experimental Notation." Soundboard Scholar 3, (1). https://digitalcommons.du.edu/sbs/vol3/iss1/7