if you were going to describe a house
<point name="topwestmostsouthmostcorneroftopwestmostsouthmostbrick"
assignment="0,0,0">
<point name="topeastmostsouthmostcorneroftopwestmostsouthmostbrick"
assignment="7.5inches,0,0">
<point name="topeastmostnorthmostcorneroftopwestmostsouthmostbrick"
assignment="0,3and5/8inches,0">
<componentclassdefinition name="brick" type="soliddefinedbylines">
<line><ep1>0,0,0</ep1><ep2>7.5inches,0,0</ep2></line>
a brick is composed of 6 faces, two ends, two sides, and a top and bottom
place a new brick adjacent to the first brick (or the last brick)
(or, say, the third brick) brick adjacency types
end to end, side to side, bottom to top, etc., plus
staggered and skewed
a cad file could comprise a record of a sequence of actions
place the corner of a brick at point 0,0,0
align the side edge origination at the 0,0,0 corner
with the x axis in a positive direction
align the end side edge of the brick originating at 0,0,0 corner
with the z axis in a negative direction
show a brick with its corners, edges, and sides numbered
