 Usage:  xm = setmask(x{,s1{,s2,...}})  
 
 Input:

  x                      n x k matrix, data. 
                         For a curve in 2D, data should be n x 2, and 
                         (typically) sorted by the first column. 
                         For a surface in 3D, data should be n x 3, sorted by 
                         the first column and the first two columns 
                         should form a grid. 
                         
  s1,s2,...              scalar, vector or matrix, string or numeric. 
                         Arguments may be 
                         keywords ("line", "surface", "text","reset"), 
                         sub-keywords ("color", "size", "style"), 
                         or attributes. Attributes may be string or numeric. 
                         Predefined string attributes can be found 
                         under [points], [lines] and [text] below. 
                         Numeric attributes need to follow the 
                         rules of setmaskp, setmaskl and setmaskt 
                         (e.g. 0..7 for basic colors). 
                         The keywords are used to separate different 
                         graphical objects (points, line, surface, 
                         text) from each other: Attributes following a 
                         keyword are assigned to the according object. 
                         Attributes without preceeding keyword are 
                         assigned to points. 
                         The "reset" keyword is special, see the note below. 
                         Text to be displayed must immediately follow 
                         the the "text" keyword. A polygon is optional, 
                         the default polygon for "line" is (1:n)' 
                         which connects points subsequently. An optional 
                         polygon definition must immediately follow 
                         the "line" keyword. 
                         Numerical values for color, size and style must 
                         be preceeded by the corresponding sub-keyword. 
                         In case of two or more attributes for one feature 
                         (e.g. "blue" and "red" together), the latest 
                         attribute is used. 
                         ==> Please check the examples! 
                         They are fairly instructive. 
                         
  [points]               color = 
                         "black", "blue", "green", "cyan", 
                         "red", "magenta", "yellow", "white" / 
                         size = 
                         "nopoint", "tiny", "small", "medium", "large", 
                         "huge" 
                         (corresponding to values 0, 1, 2, 4, 8, 12, 15 in setmaskp) / 
                         style = 
                         "empty", "point", "rectangle", "circle", "triangle", "xsymbol" 
                         "rhomb", "fillrectangle", "fillcircle", 
                         "fillrhomb", "filltriangle", "cross", "star", 
                         "grid", "gridrhomb","?" / 
                         (defaults = "black", "medium", "circle") 
                         
  [lines]                color = 
                         "black", "blue", "green", "cyan", 
                         "red", "magenta", "yellow", "white" / 
                         size = 
                         "noline", "thin", "medium", "thick", "band", "fill" 
                         (corresponding to values 0, 1, 2, 5, 14, 15 in setmaskl) / 
                         style = 
                         "invisible", "solid", "dashed", "dotted" / 
                         (defaults = "black", "medium", "solid") 
                         
  [text]                 color = 
                         "black", "blue", "green", "cyan", 
                         "red", "magenta", "yellow", "white" / 
                         size = 
                         "tiny", "small", "medium", "large", "huge" 
                         (corresponding to fontsizes 8, 12, 14, 16, 20 in setmaskt) / 
                         style = 
                         "request", "center", "right", "below", "left", "above" / 
                         (defaults = "black", "medium", "center") 
                         
 Output:

  xm                     n x k matrix, data provided with mask. 
                         
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(C) MD*TECH Method and Data Technologies, 17.8.2000
