  Countable projective limits of countable inductive limits, so-called
PLB-spaces, of weighted Banach spaces of continuous functions have recently
been investigated by Agethen, Bierstedt and Bonet, who analyzed locally convex
properties in terms of the defining double sequence of weights. We complement
their results by considering a defining sequence which is the product of two
single sequences. By associating these two sequences with a weighted
Fr\'{e}chet, resp. LB-space of continuous functions or with two weighted
Fr\'{e}chet spaces (by taking the reciprocal of one of the sequences) we derive
a representation of the PLB-space as the tensor product of a Fr\'{e}chet and a
DF-space and exhibit a connection between the invariants (DN) and ($\Omega$)
for Fr\'{e}chet spaces and locally convex properties of the PLB-space resp. of
the forementioned tensor product.
