Total number of header lines and Nasa/ames file format index
Syntax: <NLHEAD> <FFI>
Total number of lines in header (NLHEAD), and NASA-Ames file format index (FFI, for EBAS use always 1001), separated by a space.
The total number of header lines needs to be changed if the template is adapted in a way changing the number of variables contained, or if the number of metadata items is changed.
The total number of header lines is the same as the line number of the header line for the data columns, i.e. the line starting with 'start_time end_time'.