This paper intends to provide some data about the occurrence of 〈e〉 and 〈o〉 for Classical Latin (= CL) /1/ and /ŭ/ in Latin papyri and ostraca. In order to carry out a study of the incidence of some grapho-phonological phenomena within documentary texts and to examine to what extent they could be related with parameters of sociolinguistic variation, the examined texts have been collected in a corpus which has been tagged for both linguistic and extralinguistic aspects. This corpus is available in the Data-base CLaSSES (http://classes-latin-linguistics.fileli.unipi.it), created at the FILELI Department of the Uni-versity of Pisa (§ 1). The study will focus in particular on the analysis of this graphemic alternance in the Bu Njem ostraca (§ 2.1); then, it will dwell on the qualitative analysis of three lexemes in Egyptian papyri and ostraca in which a proto-Romance merger between /ĭ/ and /ē/ in /e/ and /ŭ/ and /ō/ in /o/ in tonic posi-tion might be documented. Particular attention is paid to interference phenomena with Greek (§ 2.2).