Multiple flat files format
The data that def can read (multiple files)

Structure of the Header file:
- Comment lines beginning with '#'
- Top-level (Level 0) parameter names are listed, followed by
a '>', which is used to direct def to a subfile of data
- Level 1 parameter names to be found in the subfiles
- Next are records of values for the Level 0 parameters
that will apply to the subfile listed at the end of each record.

Rules:
- Data columns may be space delimited, comma delimited, or tab delimited.
- Missing or bad data should be indicated by 'nd'. 

# Basic Hydrographic Data - Carl Wunsch
#  example of a header file
#
sta,  lat,  lon,  >
   press,temp,sal,o2,sigth 
6    38.03   -72.99  sta6.dat
7    37.93   -72.69  sta7.dat
8    37.78   -72.43  sta8.dat
9    37.61   -72.20  sta9.dat
10   37.44   -71.96  sta10.dat
...(and so on)...
The structure for each of the subfiles is the same as the one for the single flat file format. In this case (multiple files), however, the Level 0 parameters with repeating values would not be included in the subfile data. In other words, if you were submitting this sample data, the subfiles (sta6.dat, sta7.dat, etc.) would not contain the sta, lat, lon parameters.

Note: This format may be extended to 8 levels of data, or 7 levels of subfiles. Typical use, however, is for 2 levels, or one (1) level of subfile as illustrated below.