The letter is primarily about the king of Asturias purchasing a crown kept in the treasury of the church of Tours, but it also includes instructions for visiting the shrine of James, son of Zebedee, which lay in Alfonso's kingdom.
In return the church of Tours would receive the Vitas sanctorum patrum Emeritensium, a hagiography of some early Bishops of Mérida.
[7] In this passage Sisnando is anachronistically titled archbishop, centuries before the see of Iria Flavia was raised to that dignity in 1120, under Diego Gelmírez.
It has also been suggested that the title archiepiscopus is an expansion of æpiscopus (bishop), a spelling known from contemporary Spanish documents, but of which a scribe working at Tours may have been ignorant and assumed the diphthong æ represented an abbreviation of archie-.
[10] Alfonso accepted the offer and promised to arrange a "journey by sea" (navalis remigatio) for May 906 (that same year) to make the exchange.
While the anno Domini system was known in Asturias—and was used in a document recording the consecration of a new cathedral at Iria Flavia in 899—the Spanish era was hardly known outside of Spain, and even the Venerable Bede, "greatest computist of the early middle ages", was ignorant of it.
[13] The letter from Tours apparently informed Alfonso of the Viking attack of 903 in the course of which Saint Martin's, and large swathes of the city, were burnt.