  We construct by using B-spline functions a class of copulas that includes the
Bernstein copulas arising in Baker's distributions. The range of correlation of
the B-spline copulas is examined, and the Frechet--Hoeffding upper bound is
proved to be attained when the number of B-spline functions goes to infinity.
As the B-spline functions are well-known to be an order-complete weak
Tchebycheff system from which the property of total positivity of any order
follows for the maximum correlation case, the results given here extend
classical results for the Bernstein copulas. In addition, we derive in terms of
the Stirling numbers of the second kind an explicit formula for the moments of
the related B-spline functions for nonnegative real numbers.
