The edit-object is a series of line objects (extobj::role=edit, on any layer).
There can be multiple edit-objects. Parallel traces of fixed geometry at
fixed pitch are rendered under each edit object on the target layer. Joints
are properly handled as long as:
<p>
<ul>
	<li> the two edit objects are within the same bus extended object (thus
	     extending the bus must be done by grabbing the endpoint of an edit
	     line already part of the bus)
	<li> the two edit lines share an endpoint precisely (this can be done using
	     object snapping)
</ul>
<p>
Note: junctions are not possible.

<p>
<a href="../extobj">Extobj</a> details:
<ul>
	<li> the edit-object is a cover line (thickness set by the tool to match
	     final bus thickness), typically on a doc layer
	<li> the extobj attribute should be <i>bus</i>
	<li> pitch is set using extobj::pitch (coord)
	<li> trace thickness and clearance set by extobj::thickness and extobj::clearance (coord)
	<li> width (number of parallel traces) is set using extobj::width (integer)
</ul>
<p>
When a cover line is converted into a bus, the following defaults are set up:
<ul>
	<li> width to 2
	<li> trace thickness and clearance from the current drawing style
	<li> pitch is set so the empty space between two parallel lines match clearance
	<li> target layer is the current layer
</ul>
<p>
An example/test <a href="bus.lht">board</a> is available.
<p>

Demo video:
<p>
<video width="100%" controls>
	<source src="https://archive.org/download/pcb-rnd-bus/bus.ogv" type="video/ogg">
	(Your browser does not support the video tag, please download the
	<a href="https://archive.org/download/pcb-rnd-bus/bus.ogv">
	video file</a> instead.)
</video>
<p>

Steps shown in the video:
<ul>
	<li> 1. optional: create a new extobj layer group and layer. When done, this
	        can be used to avoid the edit-object interfering with the board.
	        By user convention the new layer group should be a global doc
	        layer and the purpose should be 'extobj'.
	<li> 2. draw the thick edit-line (actual thickness doesn't matter)
	<li> 3. select it and use the menu or {s c e} to convert the line into an extended object
	<li> 4. edit the geometry by grabbing the edit-object line or its endpoints;
	        extend the bus by further segments by using line refraction and moving
	        the endpoint of an existing edit-line; wireframe draw helps looking
	        under the cover line
	<li> 5. edit properties by right clicking on the 'E' mark
	<li> 6. connecting the bus wires is as easy as just drawing traces to them
	<li> 7. click any edit-line of the bus and the whole bus is selected; it
	        can be then easily copied and the new bus can be edited independent
	        of the original copy
</ul>