3 = NGS Blue Book Format : 

 NGS Blue Book format - *80* (Control Point) and *86* (Combo
 Height) Records.  INTG uses information from the *80* and *86* records in Blue
 Book files.  The Station Serial Number (SSN), the latitude and the longitude
 are read from the *80* records, the rest of the record is ignored.  Only the
 *86* record is modified by INTG - the *80* records and all other records are
 passed through without change to the output file.  Any *84* records are 
 deleted.  Information in columns 36-43 in the *86* record is
 created by INTG. 

 For more information on this format, please refer to:
   'Input Formats and Specifications of the National Geodetic Survey Data Base'
   'Volume 1. Horizontal Control Data'.
 Published by the Federal Geodetic Control Committee in September 1994 and
 available from: the National Geodetic Survey, NOAA, Silver Spring, MD 20910.

 The following input example is *80* and *86* records from a Blue Book
 file:

 004560*80*0096KNOXVILLE CT HSE              411906578  N0930548534  W 277  MIA33
 004565*86*0096 any geoid values in here     will be overwritten if ssn matches