, utScan) --otherwise its inclusion is optional. The <cite>positive</cite> attribute may have the value "up" or "down" (case insensitive).</p>
<p>For example, if an oceanographic netCDF file encodes the depth of the surface as 0 and the depth of 1000 meters as 1000 then the axis would use attributes as follows:</p>
<p>axis_name:units="meters";<br />
axis_name:positive="down";</p>
<p>If, on the other hand, the depth of 1000 meters were represented as-1000 then the value of the <cite>positive</cite> attribute