Stream file

Stream (stream file) is the on-disk dump of named drawings, numbered sheets, and shapes that tools pass around.

A rectangle, a ribbon, and an L in one drawing. A stream file can carry all three.

“Send me the stream” means the geometry handshake, not a screenshot and not a schematic PDF. A stream holds cell names, layer numbers, datatype values, and integer coordinates. It does not hold the PDK story unless someone packed extras. On disk the file is chip.gds or chip.oas, perhaps 2 gigabytes after a flatten and after OPC. “Stream in” and “stream out” mean import and export.

The usual formats are GDSII and OASIS. Older text is CIF. Boards use Gerber plots, which people do not call a stream unless they also do chips. If a partner asks for “the GDS,” that request usually means this stream. Check the top cell, the user unit (how many ticks make a micrometer), and whether hierarchy is still there. A stream flattened to please one tool can be the wrong gift for the next tool. Keep a hierarchical copy, and write the layer map in the same email as the file path.

A stream emailed without a layer map lets the other team color layer 31 as they please. Send the map, the top cell name, and the database unit.

The file formats and the readers are covered in GDSII in plain language, OASIS when GDS gets huge, and who reads a layout.