The formal names of the firm were:
-Poligrafico Alterocca, Terni (1877 - 1938)
-Società anonima Istituto poligrafico d'arte Alterocca, Terni (1938 - 1940)
-Stabilimento poligrafico Alterocca Società anonima, Terni (1940 - 1974)
-Alterocca nuova poligrafica italiana, Terni (1974 - 1980)
Early cards just use a printed line, then the Alterocca roundel. The logo STA, which stands for Stabilimento Tipografico Alterocca, was used after the death of Virgilio (maybe not straight away). The IPA/CT logo appears after the merger with Poligrafico Conti, it stands for Istituto Poligrafico Alterocca-Conti, Terni. It exists with minor variations in the shape of the boundary surrounding the letters.
The VAT mark is attributed by Stefan Kühn to Virgilio Alterocca, Terni. There are more examples at wikimedia.org/wiki/Category:Postcards_published_by_Alterocca.