Annotations

CLASS has two DRAW commands to annotate plots: i) The standard GREG DRAW command which can be accessed by typing G$\backslash$DRAW (please look at the GREG manual) and ii a special flavor of DRAW customized for annotating spectra. The CLASS flavor is the default one used when typing just DRAW The basic operations performed by this flavor of the DRAW command are:

• DRAW TEXT Xpos Ypos "Text" Centering to draw a text at position (Xpos,Ypos) (in current units) with the specified centering code. This command works more or less like the GREG command of same name. Please refer to the GREG manual for details. In particular, you can include Greek letters and Symbols in the text using the escape character $\backslash$. A strange thing may appear on the screen, but it is O.K. on the plot.
• DRAW UPPER Xpos "Text" to draw a vertically oriented text at position Xpos, with a vertical line connecting the beginning of the text to the current spectrum. This text and line are written at position Xpos, in units of the upper axis. Typically, this command is used to mark spectral line identifications.
• DRAW LOWER Xpos "Text" same as above, but with Xpos in units of the lower axis.
• DRAW WINDOW [Level] shows the current line windows by marks on the graphic plot. Level is an optional arguments indicating at what Y value the marker should be put (Default 0).
• DRAW MASK [Level] same as above but for the current masks.
• DRAW KILL [Channel] kills the specified channel (current one if using the cursor) by attributing it the “blanking” or “undefined” value.
• DRAW FILL [Channel] Fills the specified channel (current one if using the cursor) by interpolation between the nearest non-blanked channels. The channel must have been killed before.

Any other character will not draw anything, but simply returns the cursor position, with corresponding values of the velocity, frequency, image frequency, channel number.