Every Plot is also a Frame, so can be used to obtain the values of
Frame attributes such as a Title, axis Labels, axis Units,
etc., which are typically used when displaying data and/or
coordinates. These attributes are, as for any FrameSet, derived from
the current Frame of the Plot (
). They are
also used automatically when using the Plot to plot coordinate axes
and coordinate grids (e.g. for labelling
them--
).
Because the current Frame of a Plot represents physical coordinates,
any Frame operation applied to the Plot will effectively be working in
this coordinate system. For example, the AST_DISTANCE and AST_OFFSET
routines will compute distances and offsets in physical coordinate
space, and AST_FORMAT will format physical coordinates in an
appropriate way for display.
AST A Library for Handling World Coordinate Systems in Astronomy