This database of 448 working maps was taken from the Atlas linguistique et ethnographique de la Gascogne (ALG), vol. I-III, whose data were collected between 1946 and 1952 and published by Jean Séguy between 1954 and 1958. For the production of these 448 working maps, 237 out of the total of 1092 original maps of ALG I-III were used.
In terms of categories, 348 of the 448 working maps belong to phonetics (of which 167 belong to consonantism, 125 to vocalism and 56 to phonetic macro-phenomena) and 100 to the lexicon (vocabulary).