The sets of core samples were distributed to over 120 laboratories that had returned an original questionnaire seeking expressions of interest in participation. A reporting format for the results was also agreed and distributed to the laboratories at the same time. This is shown in Table 2.1. Laboratories were originally given 1 yr (i.e., to August 2000) to complete the analyses and return the results, but this was later extended to December 2000. In this section, we briefly describe the laboratory characteristics and the overall response rate of the participating laboratories.