OpenLogPlot Fill Options

The six most used curve fill options for OpenLogPlot are shown below. Basically, these allow for fill between track edges and a curve, between a curve and a cut-off, or between curves. Three remaining options, not shown below, are: fill between the left-edge and the cut-off; fill from the cut-off to the right-edge; and fill from the left-edge to the right-edge.
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Fill is controlled by a test. The test can compare a curve to a cut-off or another curve. As a special case, the test can be set to "TRUE". If the test is true, then the TRUEAREA is filled. If the test is false, the FALSEAREA is filled. Either of these can be set to NULL if no fill is wanted in that case.
Curves are specified by variables (C1, C2, C3, etc.) in the test and fill specifications. These map to the first, second, third, etc. curves listed for this track in the track template. The cut-off is referenced by CO (the letters 'C' and 'O' - not zero!) and maps to the cut-off specified for the track (see track template).