Marks a position on a graphics device
" POLY" , " CHAIN" or " BOX" . " NONE" – An immediate return is made without any graphics being drawn.
" MARK" – Each position is marked by the symbol specified by argument MARKER.
" POLY" – Causes each position to be joined by a line to the previous position marked. These lines
may be geodesic (in the Current Frame of the Plot) or straight (on the screen), as specified by
argument GEO.
" CHAIN" – This is a combination of " Mark" and " Poly" . Each position is marked by a symbol and
joined by a line to the previous position. Arguments MARKER, GEO, and CLOSE are used to specify
the symbols and lines to use.
" BOX" – An empty rectangle with edges parallel to the axes is drawn extending between the supplied
position and the previous position.
" VLINE" – A vertical line is drawn through the position covering the entire height of the
Plot.
" HLINE" – A horizontal line is drawn through the position covering the entire height of the
Plot.
" CROSS" – A full-screen cross-hair is drawn at the position, i.e. a combination of Vline and
Hline.
" TEXT" – The text string specified by argument TEXT is displayed, horizontally, and centred on the
supplied position.
" BLANK" – Nothing is drawn.
" REGION" – The AST Region given by REGION is outlined.
" MARKER" or " CHAIN" . " PLOT" , " CHAIN" or " BOX" . " TEXT" . Trailing spaces are ignored. " Text" ). This should be a string of two characters; the first should be " B" , "
C" or " T" , meaning bottom, centre or top. The second should be " L" , " C" or " R" , meaning left,
centre or right. The text is displayed so that the position supplied in POS is at the specified point
within the displayed text string. " REGION" . In order to save time calling AST_CONVERT for every
Region, the first Region to be plotted using this routine defines the co-ordinate frame for all
subsequent Regions draw by later invocations of this routine. If in fact, later Regions may have a
different co-ordinate frame, then this routine should be called with MODE=REGION and
REGION=AST__NULL. This will cause the current Region co-ordinate frame to be forgotten so that
the next non-NULL Region to be draw will define a new current co-ordinate frame for
subsequent Regions.