Hi, I primarily use Splus for analysing TCP/IP traffic at the packet level. Several years ago, I hacked together functions using the .C call for bit operations: bitAnd, bitOr, bitFlip, bitShiftL, bitShiftR, bitXor and crc(char). Are there any more standard alternatives for these? If not, and, if any there is any interest, I would be happy to help package what I have for distribution. Additionally, I would interested in hearing offline from anyone using R/Splus communication network analysis. Thanks, Steve Dutky TF Rockville Network Services 301-545-4113 desk 800-532-2382 24x7 301-325-8146 cell