  If E is a locally convex topological vector space, let P(E) be the
pre-ordered set of all continuous seminorms on E. We study, on the one hand,
for g an infinite cardinal those locally convex spaces E which have the
g-neighbourhood property in the sense of E. Jorda, i.e., spaces in which all
sets M of continuous seminorms of cardinality up to g have an upper bound in
P(E). On the other hand, we study bilinear maps b from a product of locally
convex spaces E_1 and E_2 to a locally convex space F, which admit "product
estimates" in the sense that for all p_{i,j} in P(F), i,j=1,2,..., there exist
p_i in P(E_1) and q_j in P(E_2) such that p_{i,j}(b(x,y)) <= p_i(x)q_j(y) for
all x in E_1, y in E_2. The relations between these concepts are explored, and
examples given. The main applications concern spaces C^r_c(M,E)$ of
vector-valued test functions on manifolds.
