If the file is fixed-width, RPI undertakes initial determination of its field boundaries. The first [x] rows of file are analyzed (where [x] is defined by system configuration setting NumberFirstLinesToRead). Note that the file’s first line is not skipped.
RPI looks for the occurrence of spaces at the same location within more than [y]% of file (where [y] is defined by system configuration setting FixedWidthSpaceThreshold) to determine locations of likely field boundaries. No initial schema or content analysis is performed. The file’s schema is only analyzed during re-analysis.