Postprint version. Published in Journal of Integral Equations and Operator Theory, Volume 23, Issue 1, March 1, 1995, pages 1-48. Copyright © 1995 Springer. The original publication is available at http://dx.doi.org/10.1007/BF01261201.
NOTE: At the time of publication, the author Mark Stankus was not yet affiliated with Cal Poly.