[[Image:PMOM11.png|thumb|250px|EM.Picasso's Navigation Tree.]]
[[Image:PMOM9.png|thumb|270px|EM.Picasso's Add Substrate Layer dialog.]]
=== Understanding the Background Structure ===
The Stack-up Settings dialog has two tabs: '''Layer Hierarchy''' and '''Embedded Sets'''. The Layer Hierarchy tab has a table that shows all the background layers in hierarchical order from the top half-space to the bottom half-space. It also lists the material composition of each layer, Z-coordinate of the bottom of each layer, its thickness (in project units) and material properties: permittivity (ε<sub>r</sub>), permeability (μ<sub>r</sub>), electric conductivity (σ) and magnetic conductivity (σ<sub>m</sub>). There is also a column that lists the names of embedded object sets inside each substrate layer, if any.
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<td> [[Image:PMOM8(1).png|thumb|550px|EM.Picasso's Layer Stack-up Settings dialog with the initial default values.]] </td>
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You can add new layers to your project's stack-up or delete its layers, or move layers up or down and thus change the layer hierarchy. To add a new background layer, click the arrow symbol on the {{key|Insertâ¦}} button at the bottom of the dialog and select '''Substrate Layer''' from the button's dropdown list. A new dialog opens up where you can enter a label for the new layer and values for its material properties and thickness in project units. You can delete a layer by selecting its row in the table and clicking the '''Delete''' button. To move a layer up and down, click on its row to select and highlight it. Then click either the '''Move Up''' or '''Move Down''' buttons consecutively to move the selected layer to the desired location in the stack-up. Note that you cannot delete or move the top or bottom half-spaces. After creating a substrate layer, you can always edit its properties in the Layer Stack-up Settings dialog. Click on any layer's row in the table to select and highlight it and then click the {{key|Edit}} button. The substrate layer dialog opens up, where you can change the layer's label and assigned color as well as its constitutive [[parameters]].
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<td> [[Image:PMOM8(1)PMOM9.png|thumb|550px270px|EM.Picasso's Add Substrate Layer Stack-up Settings dialog with the initial default values.]] </td>
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<td> [[Image:PMOM12.png|thumb|550px450px|EM.Picasso's Layer Stack-up Settings dialog showing a multilayer substrate configuration.]] </td>
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