GDS options are controlled with the "GDS" preferences (in menu File / Preferences..., "I/O" section, "GDS" tab).

In GDS files, there are no names for each layer, just numbers. It is important that Electric know the meaning of each number so that it can properly read and write GDS files. This dialog lets you edit those GDS layer numbers and assign them to different Electric layers.

The list on the left shows all of the Electric layers. By clicking on a layer name, its GDS layer numbers are shown in the top-right and can be edited. In addition to GDS layer numbers to use for layout, there are also two other types of GDS layer numbers: a pin layer (for exports) and a text layer (for export names).

These dialog elements apply to writing GDS:

- "Output merges Boxes". This controls the merging of adjoining geometry. This is an issue because of the duplication and overlap that occurs wherever arcs and nodes meet. The default action is to write each node and arc individually. This makes the file larger because of redundant box information, however it is faster to generate and uses simpler constructs. If you check this item, all connecting regions on the same layer are merged into one complex polygon. This requires more processing, produces a smaller file, and generates more complex constructs.
- "Output Writes export Pins". This controls whether pins are written to the GDS file for each export. If checked, and there is a valid pin layer, then it is written.
- "Output all upper case". This controls whether the GDS file uses all upper case. The default is to mix upper and lower case, but some systems insist on upper-case GDS.
- "Output default text layer". This is the layer number to use when writing text. When pins are being written, and there is a text layer number associated with the appropriate Electric layer, then that layer number is used instead of this default number.