Specify the common terms used when tEDAx blocks describe geometry. Any specific block description may deviate from the terms listed here; if a block specification doesn't explicitly deviate, the terms below are implied.
Default orientation: we are looking down at the board from the top side. The origin of the coordinate system is on the top left, X coordinates increase to the right, Y coordinates increase downward, Z coordinate increasing towards the bottom side of the board. Coordinates are expressed in mm as real decimal values, e.g. "0.065" means 0.065 mm. The number of digits after the decimal point shall not exceed 9 (nanometer precision). There is no expectation about the precision of implementations - they are free to discard decimal digits and apply their preferred rounding rules.
For arc angles, 0 degree is at 9 o'clock and positive angles are CCW.
Unless otherwise specified, a trace object is specified with its centerline and its thickness. A trace object is usually a line segment or an arc. Such trace objects usually have round ends: they end in a filled half circle, extending from the endpoint onwards with half the thickness.
A polygon is specified by its contour. The contour consists of straight line segment with implied width of 0. The contour is not self-intersecting and has at least 3 corners. The polygon has only one contour - there are no holes. The points of the contour are specified in an ordered list. There is no requirement that this list needs to be CW or CCW. The starting point is not repeated as an ending point, that is, a triangle polygon has exactly 3 points on its contour.
A hole is always round and is specified by its diameter. Unless otherwise specified, a hole goes thru all layers (there is no blind or buried hole).
Some copper objects may have a clearance to nearby copper polygons. The clearance is specified as the distance between the outer copper edge of the copper object and the surrounding copper polygon.