Layer Mapping

GDSII geometry entities such as boundaries and paths are tagged with two attributes: a layer and a datatype. The original GDSII specification allowed these attributes to range from 0-63, but later implementations of GDSII support layer/datatype attributes from 0-8191.

When merging GDSII files, the user can specify which layer/datatypes will be passed to the output file from each of the merged files.

The list looks like the following:

3:0,6:0,6:1,15:0,17:0,17:1,25:0,26:0,29:0,30:0,31:0,31:1,32:0,32:1,33:0,33:1,34:0,34:1,35:0,35:1

where the first number is the layer attribute, followed by a colon (:), followed by the datatype attribute. The comma acts as a delimiter.

Shifting Layers

When "overlaying" two similar files for comparison purposes, one might want also shift the layers from one of the files so that a GDSII viewer can separate them out. This is accomplished by providing a list for the output file.

Example

File A and File B have data of interest on layers 3:0,6:0,6:1,15:0,17:0,17:1. In order to visualize any changes made we want to shift (in the output) the layers in File B by 100. That will make it easy to compare layer by layer.

Then our overlay program would have two separate entries:

It is necessary that an input and output layer list have the same number of elements. So even if you want to shift just a single layer, you need to specify all layers/datatype pairs in the output layer box.

Suppose we just want to shift layer 6 to 106 in File B. We still have to match the other layers.