Instead of reading input in lines as sed, this program reads arbitrary blocks from an input stream and performs byte-related transformations on found blocks. Blocks can be defined using start or stop strings, stream offset and block length, or a combination. Basic editing commands include delete, replace, search and replace, binary operations, append, and bcd-to-ASCII conversion. For examining the input stream, it contains some grep-like features like printing the input file name, stream offset and block number of found blocks. Block contents can also be printed in different formats like hex, octal, ASCII and binary.