Layers

Inside of each STEP is one or more layer directories. The layer directory contains the drawable "feature" file that are converted to RS274X.

The layer's directory name is appended to the RS274X file generated (along with the layer number)

The layer attributes control mirroring, scaling in X and Y and polarity. These transformations are reflected in the RS274X header. Compensation attribute (if specified) is ignored as their is no equivalent in RS274X. This file need not be present.

Features

Each ODB++ layer's feature file contains the elements that are converted to RS274X. The feature file has four sections:

• Symbols - contains the names of all of the symbols used in the features list.

• Attributes Table - Contains the names of attributes used by the features in the file. This data is ignored.

• Attribute Text - Contains a list of text strings which are values for textual attributes. This data is ignored.

• Features List - Contains the actual features data. This data is processed and converted into RS274X.

A line using round or square aperture will be converted to a draw. A line may also be used for polygons or surfaces and will then be converted into a G36/G37. A line may be used to build a symbol and will then be converted into either a macro primitive or booleanized as G36/G37.

A pad will point to a symbol and will be converted, whenever possible, into a flash.

An arc, if drawn using a round/square aperture will be converted into a Gerber draw. If it is part of surface definition then it will be converted into a G36/G37 boundary. If it is part of a symbol then in may be converted into a macro pimitive or booleanized into an G36/G37 figure.

The RS274X text functions are not normally supported by photoplotters. Therefore any features of type text will be stroked using a character table built to match that of the Valor CAD system. Details on Text Rendering

Early versions will not support the barcode feature.

An ODB++ surface must first be evaluated to define the boundary and any holes or islands. A boolean operation must then be performed on the boundaries to produce a G36/G37 polygon that either uses re-entrant polygon to support islands or slices the surface into a suitable number of pieces to eliminate all holes/islands. Details on Surface Processing