The situation I am facing is a b-file with gaps. For concreteness: 0 - 198 known 199 - 207 unknown 208 - 213 known 194 2 195 0 196 0 197 2 198 2 199 * 200 * 201 * 202 * 203 * 204 * 205 * 206 * 207 * 208 22 209 0 210 0 211 0 212 4 213 4 Is something like this allowed? Peter