The standard Surfer® input file format is comprised of header records and data records :
• Data records are space-delimited XYZ type data. This means that each data record contains at least 3 fields: an x-coordinate location, a y-coordinate location, and the value for at least one z variate measured at that x-y location (single-dimension transects will have only x-coordinate and z variate data values). Additional fields can hold other variates for that location, e.g. sample ID, other measured z-variates.
• A single header record precedes the data records and contains field (variate) names or column titles for the data record fields. Names are space-delimited so they must be single words (e.g. "mEast mNorth Nitrate") in order that they be properly assigned to their columns. You can allow names to be delimited by commas or other characters by changing this to a Custom Format in the File Import Properties window (e.g. "meters East, meters North, Nitrate (ug/L)" ).
• Missing values are indicated by blank fields. For files where there is more than one z-variate per record, a missing value for any field in the record means that the entire record will be treated as missing. (To avoid this problem use comma-delimited data records.)
Any of these parameters (field delimiters, number of header records, missing value indicators, etc.) can be changed to a custom format from the Import Text File window. Note that some Surfer™ files are comma-delimited rather than space-delimited.
The following listing is the first 9 records of a standard Surfer™ input file that has fields for an x-coordinate, a y-coordinate, and one z variate. Note the three variate names in record 1 and the missing values in records 5 and 9:
Xdata Ydata Z1data
4.5 11.9 0.42
2.7 29.4 0.45
1.6 32.6 0.08
4.1 44.5
0.6 64 0.14
2.4 71.8 0.32
7.8 3.5 0.12
6.7 10.2
6.7 16.3 0.49