The structures can be a mixture of LINE, CURVE, and FILLETSHARP structures. These have similar forms and the second field, bType, identifies the type of the structure.

Starting at the structure addressed by pLine, the handling routine examines the bType field of each structure in turn. If bType is LINE_IDENTIFIER, the handling routine draws the line. Otherwise, it uses the value of the npcvNext field to skip to the next structure. This process continues until the handling routine has drawn the number of lines specified by cLines. Before drawing a line, the handling routine must check the CURVE_DO_FIRST_PEL flag to determine whether it should draw the first pel of the line. When the line passes between two pel positions, the presentation driver should round down to the nearest pel for values of 0.5 or less.

The call to GreDrawLinesInPath in the presentation driver is made by the graphics engine. Note that the coordinates are passed as screen coordinates (device coordinates + DC origin), and the lines are already completely clipped.