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7.2 Layout File Format

The layout file describes a complete layout including symbols, vias, elements and layers with lines, rectangles and text. This is the most complex file of all. As Pcb has evolved, the file format has changed several times to accommodate new features. Pcb has always been able to read all older versions of the .pcb file. This allows the migration of older designs to newer versions of the program. Obviously older versions of Pcb will not be able to properly read layout files stored in newer versions of the file format.

In practice it is very common for footprint libraries to contain elements which have been defined in various versions of the Pcb file format. When faced with trying to understand an element file or layout file which includes syntax not defined here, the best approach is to examine the file src/parse_y.y which is the definitive definition of the file format.

The PCB layout file contains the following contents, in this order (individual items are defined in File Syntax:

PCB
This names the board and sets its size
Grid
Optional.
Cursor
Optional.
Flags
Optional.
Groups
Optional.
Styles
Optional.
Symbols
Optional.
Vias, Rats, Layers, and Elements
These may occur in any order, at this point in the file.
Netlists
Optional.