I want to generate a ppp object (spastat R package) using the command 'ppp' and 3 vectors containing coordinates and numeric mark data, but I get an error I don't understand. The command is: index10.ppp <- ppp(x, y, c(20,240), c(140,780), marks=z) where: x is a numeric vector of integers that represents the x-coordinate in the plane y is a numeric vector of integers that represents the y-coordinate in the plane z is a numeric vector of doubles (float) that represents the values of an index measured at each x-y point The values given for owin are the corners of the experimental plot Here is the error message: "Attempted to create point pattern with 1 columns of mark data; multidimensional marks are not yet implemented" How can 1 column of data be multidimensional? Does this error refer to my use of integer coordinates and double marks? Is there a work around? I'm using R for Mac OS X. The version of R is: 1.15, framework R 2.3.0. The version of spastat is: 1.9-1. Any advice is appreciated. MF