GDSII/GDS2 is a binary file format that represents the layers needed to produce an ASIC. In the OpenLane flow, Magic is used to ‘stream’ the final GDS2 files. All shapes are assigned to a given GDS2 layer, and each layer ends up being used to create a mask, although often this may involve the combination of one or more GDS2 layers to form one mask, and the shapes are often grown, or shrunk, or merged and thus what ends up on the mask may not be the same as what was drawn by the designer.
