This data-set contains the locations of cattle herds in Cornwall, UK,
   that have tested positive for bovine tuberculosis. The record for each
   herd contians the following information:

              x,y: location
             year: year of testing
      spoligotype: a qualitative genetic marker

   An analysis of the data is reported in:

   DIGGLE, P.J., ZHENG, P. and DURR, P. (2005). Non-parametric estimation of spatial
      segregation in a multivariate point process. Applied Statistics, 54, 645-658.