In order to make a drawing it is useful to understand the underlying philosophy which is based on the postscript imaging model. A very brief introduction to the postscript imaging model will be presented here. To make a postscript like drawing it is first necessary to generate a current path. A path is built using functions such as moveto(x1,y1); and lineto(x2,y2 );. These functions by themselves do not cause anything to appear on the page. Once a current path is specified then it can be stroked or filled. A path is stroked to the page using the current line width, style, and colour with the stroke(); function. This function also resets the current path to null. The current values of width etc. are set using the set(attribute,value); function were it is advisable to use the predefined values in splot.h for the attributes and values to improve readability of the code (The easiest thing is to select them from the pull down menu). Alternatively a closed current path can be filled with the current colour using the fill(); command. This also resets the current path to null. At this point a virtual page in memory has been marked but the actual physical page has not yet been affected. This allows subsequent drawing commands to draw over what is already there. The "paint" is in effect opaque. This means that it is possible to draw over something with the colour set to white and in effect white it out. This can be put to good use for fixing blemishes as shown in some of the example files. The virtual page is transferred to the physical page using the showpage(); or function or at the end of file execution by default. However, only things within the current clip window are transferred to the physical page. The crucial points to remember are that in order to see anything on the physical page (either on the screen or a printer page) a path must first be stroked or filled and then finally transferred using showpage();. This imaging model is very powerful and allows essentially anything to be drawn given the a suite of path building functions. More details on these and other postscript issues can be found in a standard postscript reference.