MPE currently provides 3 different logfile formats, they are ALOG, CLOG and SLOG. ALOG is provided for backward compatibility purpose and is no longer developed. CLOG is a simple collections of singly timestamped events and is understood by Jumpshot-2. CLOG is the first logfile format in MPE to be read by a Java based visualization tool. SLOG is an abbreviation for Scalable LOGfile format and is based on doubly timestamped states. The scalability of SLOG comes from separating all states in the logfile into frames of data, each is small enough to be processed efficiently by the display program, Jumpshot-3. At the same time, when two adjacent frames are compared sides by sides, states and arrows will be showed leaving the earlier frame and then entering into later frame seamlessly. SLOG and Jumpshot-3 are capable to handle logfile in the Giga Byte range. And a simple statistics of state activties is kept by SLOG and displayed by the Preview window of Jumpshot-3 to guide user to locate interesting frame. See document mpe/viewers/jumpshot-3/doc/TourStepByStep.pdf for more details.