The data processed within a window can be controlled by specifying start and stop times at a particular offset using the OFFSET_CONTROL parameter set. Offset limiting provides a method to ensure that large amplitude first arrivals are not used in the analysis of noise. The trace header literal used to define the offsets is specified by the OFFSET_LIT parameter, and the offset is specified by the OFFSET_DIST parameter. The OFFSET_LIMIT_START and OFFSET_LIMIT_STOP parameters specify the start and stop times, respectively. Start and stop times are linearly interpolated between the specified offsets. The offset, start, and stop values may be spatially varied by specifying a different set of these values for specific control points (CNTRLPT parameter). The trace header literal used to identify the control points is specified by the CNTRLPT_LIT parameter. Any data within a window beginning before the offset limiting start time is not processed. Likewise, any data within a window ending after the offset limiting stop time is not processed. If the data within a window is limited more than half its original length, it is not used.