The PHASE_SEG1 and PHASE_SEG2 phase-buffer parts of the message bit time are used to compensate for edge-phase errors. They can be lengthened or shortened by resynchronization to establish the correct sampling point. The values for the four bit-time parameters typically are defined in the top-level specification for a network. They are set by taking into account factors such as wiring length, bandwidth requirement, operating environment, and so on. It's important to remember that the timing parameter values must be the same for all nodes.