BLANK

 BLANK = blnk

 blnk  Is a character scalar memory reference that is 
       assigned one of the following values:

 'NULL'      If null blank control is in effect for the
             file open for formatted I/O.  (Blanks are 
             ignored unless the field is all blanks, in
             which case it is treated as zero.)

 'ZERO'      If zero blank control is in effect.  (All 
             blanks other than leading blanks are treated 
             as zeros.)

 'UNDEFINED' If the file is not open or if the existing
             file is not open for formatted I/O.