“…By the local description of double vector bundles, presented in [8], the notion of double vector bundles in the sense of the present paper is equivalent to the one in the book [11]. Product preserving (gauge) bundle functors are studied in [1,6,7,9,10,12,13,14,16,17,18]. Liftings of vector fields to product preserving (gauge) bundle functors are studied in [5,10,14].…”