These would, for example, point to the entities between which a dimension is defined, or point to two arcs used to define a tangent line. The effect of changing the length of the shaft by 15 mm would be to move the dimensions associated with that end of the shaft, and to change the values of any dimension affected by the change. Each entity in a model may be associated with one or more name-value attributes, or each attribute may be associated with one or more entities. Questions 6 to 10 are largely book-work, or direct repetition of material from the lectures. Not all of the standards material is covered in any particular year, so don't worry if the questions do not seem to be familiar.
Style sets the style for pixel fills.
XCreatePixmap creates an array of off-screen pixels in the server. XCreateWindow creates a window to be used fro drawing on the server's screen. XFillRectangle sets pixels in a rectangle to a fill pattern.