For a countable inductive limit of metrizable locally convex spaces, a
condition (M) (in the sense of RETAKH) by operators is introduced and
the incidence of this property for the interchangeability of (LF)-spa
ces and tensor products with a Banach space is discussed. Examples are
given in the setting of weighted (LF)-spaces of continuous functions,
Kothe (LF)-sequence spaces, weighted (LB)-spaces of holomorphic funct
ions on balanced domains.