C_Annotation Keyword
Used With Routines:  CONTOUR,  CONTOURFS,  CONTOUR2,  MAP_CONTOUR
Corresponding System Variable: None.
Sets the label that will be drawn on each contour.
Usually, contours are labeled with their value. This parameter, a vector of strings, allows any text to be specified. The first label is used for the first contour drawn, and so forth. If the Levels keyword is specified, the elements of C_Annotation correspond directly to the levels specified, otherwise, they correspond to the default levels chosen by the contour procedure. If there are more contour levels than elements in C_Annotation, the remaining levels are labeled with their values.
 
note
If the CONTOUR2 Fill keyword is used, labeling is disabled. Refer to the description of CONTOUR2 in the PV-WAVE Reference for an example of how to create a filled contour plot with labels.
Example
To produce a contour plot with three levels labeled “low”, “medium”, and “high”:
CONTOUR, Z, Levels=[0.0, 0.5, 1.0], $
   C_Annotation=['low', 'medium', 'high']
Use of this keyword implies use of the Follow keyword.