<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE language SYSTEM "klayout_doc.dtd">

<doc>

  <title>Removing And Adding Layers To The Layer Set</title>
  <keyword name="Layer properties"/>
  <keyword name="Add layers to layer properties"/>
  <keyword name="Remove layers from layer properties"/>

  <p>
  The layers shown in the layer list are rather "pointers" to the actual
  layout layers and not representing the actual layers. Because of this, these
  layers are more precisely referred to as "views". Layers can be removed and
  created again without affecting the actual layout data.
  </p>

  <p>
  To create a layer, choose "Insert View" from the layer context menu (right 
  mouse button click on the layer list). Then, an input dialog prompts for the
  source specification. The source specification tells, from which actual data
  layer to take the displayed data from. The most simple form of a source 
  specification is "layer/datatype" (i.e. "5/0") or the layer name, if an OASIS
  layer name is present. This specification can be enhanced by a layout index.
  The first layout loaded in the panel is referred to which "@1" or by omitting 
  this specification. The source specification "10/5@2" therefore refers to layer
  10, datatype 5 of the second layout loaded in the panel.
  </p>

  <p>
  Source specifications can be wildcarded. That means, either layer, datatype
  or layout index can be specified by "*". In this case, such a layer must
  be contained in a group and the group parent must provide the missing specifications.
  For example, if a layer is specified "10/*" and the parent is specified "*/5", the
  effective layer looked for will be "10/5". Unlike the behaviour for the display
  styles, the children override (or specialize) the parent's definition in the 
  case of the source specification.
  </p>

  <p>
  The layer list can be cleaned up to remove layer views that do not correspond to
  actual layout layers using the function "Clean up views" from the context menu.
  Similar, layers that are present in the layout but for which there is no view can
  be added using the "Add other views" method.
  </p>

</doc>

