The Specificity measure (Lafon, 1980) is one of the core analytic features in textometric software like TXM, IRaMuTeQ, Trameur, Hyperbase, DtmVic, Lexico. It implements a precise and straightforward modeling of word frequency variation, and adopts a convenient notation that converts probabilities into magnitudes. This operational clarity is an asset in the Humanities from a hermeneutic point of view, and it helps understand and manage the model limitations. The Specificity measure does not modelize keyness, nor language, but it provides a meaningful benchmark for frequency evaluation. As a Fisher's exact test, it is valid over the entire frequency range, and it does not require any additional confidence test. The Specificity measure applies a bag-of-words reduction, however this may be overcome by using Specificity in combination with other text analysis tools or in the context of a rich corpus encoding, as can be illustrated within TXM software. Reference: Lafon, Pierre (1980). Sur la variabilité de la fréquence des formes dans un corpus. Mots, 1, 127-165. http://www.persee.fr/web/revues/home/prescript/article/mots_0243-6450_1980_num_1_1_1008