2.4.6. element objects
+2.4.6. element objects and footprints
++An element is an instance of a footprint that is already placed on the +board or loaded into a paste buffer. + +
+In the footprint form the construct is small and flexible. Ot describes +all the physical parts, like pins, pads, silk lines. In the same time a +footprint leaves many details blank, e.g. it doesn't specify exact layers, +it doesn't a have font and the refdes is random. + +
+When the footprint is loaded, it becomes an element. The element inherits all +the physical properties and the blank details are filled in with the data taken +from the current board: the layer binding is done, all parts of the element +lands on a specific board layer; the refdes is rendered using the font in +the current board. + +
+The footprint -> element instantiation is also a copy. Once the element +is created from a footprint, the element is a self-containing object and +does not have any direct reference to the footprint it was once derived from. +Changes to the original footprint will not affect the elements. + +
+In other words, a footprint is an abstract recipe, part of a +library, while an element is a land pattern already embedded in a +specific design and describes actual copper and silk. + +
+Currently an element or footprint can contain the following objects: +
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+
- pins - same as vias, but also have a pin number and pin name within the element; they affect all layers +
- pads - short lines, usually with rectangle end cap; pads also have number and name; they affect the top or bottom copper layer only +
- silk lines - on top or bottom silk layer +
- silk arcs - on top or bottom silk layer +
- silk text - limited: only one of refdes, element name and element value is displayed at the time +