Level 2 Help for ZIPCOL2

INP number 1 is the IBIS interface file being modified.
INP number 2 is the secondary input interface file.

INCOL is used to specify columns in INP number 1, which are used as matching
keys. These keys are in columns X1 to Xk.

OUTCOL is used to specify columns Y1 to Yn of INT1 which will receive data
when INCOL matches are found.

NULL is used to specify the values C1 to Cn that are to be used as data values
for the corresponding columns if no match is found.  The default is zero values.

If mixed alphabetic and numeric columns are zipped, these apply to the
numeric columns in order, skipping over the alpha columns.

 Same as NULL, used to input a character string.  the default is blanks.

If mixed alphabetic and numeric columns are zipped, these apply to the
alpha columns in order, skipping over the numeric columns.

Columns D1 toDk are the matching keys in the secondary input file. Column
numbers E1 to En specify the columns where data to be transferred to the
OUTCOL columns in INP number 1 are found. The number of 'D' values and 'E'
values must correspond to the number of values following INCOL and OUTCOL
respectively.

There was some confusion in the old zipcol, that not specifying the NULL
keyword would mean that data values are unchanged.  Now the user has to 
explicitly use the 'NONULL keyword to get this case.  The default of NULL
is all zero values.