GDS II is a database file format which is the de facto industry
standard for data exchange of integrated circuit or IC layout artwork.
It is a binary file format representing planar geometric shapes, text
labels, and other information about the layout in hierarchical form.
The data can be used to reconstruct all or part of the artwork to be
used in sharing layouts, transferring artwork between different tools,
or creating photo masks. Initially, GDS II was designed as a format
used to control integrated circuit photo mask plotting. Despite its
limited set of features and low data density, it became the industry
conventional format for transfer of IC layout data between design
tools of different vendors, all of which operated with proprietary
data formats. It was originally developed by Calma for its layout
design software, "Graphic Data System" ("GDS") and "GDS II". Now the
format is owned by Cadence Design Systems.
GDS II files are usually the final output product of the IC design
cycle and are given to IC foundries for IC fabrication. GDS II files
were originally placed on magnetic tapes. This moment was fittingly
called tape out though it is not the original root of the term.
Objects contained in a GDS II file are grouped by assigning numeric
attributes to them including "layer number", "datatype" or "texttype".
While these attributes were designed to correspond to the "layers of
material" used in manufacturing an integrated circuit, their meaning
rapidly became more abstract to reflect the way that the physical
layout is designed. As of October 2004, many EDA software vendors have
begun to support a new format, OASIS, which may replace GDS I
source:http://www.layouteditor.net/wiki/GDSII
