datakit : software editor, software and tools for conversion of native and neutral formats cad/cam.

The STEP protocols AP203 and AP214 are the mostly used ones in the domain of 3D CAD :
+ AP203 - Configuration Control Design - applies to Mechanical CAD in general,
+ AP214 - Core Data for Automotive Mechanical Design Process - is more focused on Automotive Industry.

However the really addressed scope of AP214 in mechanical CAD is roughly equivalent to AP203, overall after the last update of AP203, known as Edition 2 (AP203E2).

As a notice, the works on PDM data, which have defined STEP PDM Schema, have been integrated into these protocols as into others.

Hence, these 2 AP's cover most of the actual commercial use of STEP. The DATAKIT reader and writer for STEP are designed to exchange 3D CAD data using AP203 or AP214.

AP203 : Configuration Controlled 3D Designs of Mechanical Parts and Assemblies

Scope of AP203 (Edition 1) covers :

Products as mechanical parts and assemblies,
Data for configuration control applied to design phase,
Data related to the documentation of design change process, approval, security classification,
Geometrical data as : wireframe, surfacic models, faceted models, manifold surfaces and solids (BREP).

It does not cover (in particular) :

Constructive Solid Geometry (and more generally, Construction History),
Data which doen't apply to design phase (such as manufacturing),
Graphical presentations.

From that rather limited list, some additional extensions have been proposed, to cover graphics, dimensioning, etc.. already covered in AP214. This has leaded to an update, known as AP203 Edition 2 (AP203E2).

AP203 Edition 2 : evolution of AP203

This evolution has been firstly published in 2004, it is to be closed by end 2009.

With Edition 2, AP203 provides better interoperability with AP214. From AP203 (Edition 1), this Edition 2 adds, in a modular way :

Colors and Layers,
Textual annotations associated to the geometry,
Geometrical Dimensions and Tolerances (GD&T), with graphical presentations,
Validation Properties (Global, as volume, area, center; Local as Clouds of Points),
Construction History in 3D,
Definitions for PDM to be added too (specially, configuration management).

Already additional definitions are in preparation, in particular to complete the Geometrical Dimensions and Tolerances (GD&T).

AP214 : Core Data for Automotive Mechanical Design Process

The whole scope of AP214 covers :

Products as mechanical parts , assemblies, tools used by manufacturing (in principle applied to description of cars) ,
Information for process plan, configuration control, applied to design phase
Data related to the documentation of design change process, approval, security classification,
Geometrical data as : wireframe, surfacic models, faceted models, manifold surfaces and solids (BREP), constructive solid geometry, hybrid models
References to product data represented in an other format than STEP
Kinematic structures,
Tolerance data, Surface conditions.

In regard of this scope, limitations apply. These domains are in practice not covered :

Parametric representation of shapes,
Continous kinematics simulations over time,
Data related to finite element analysis (see AP209),
Data related to particular technologies such as pneumatic, hydraulic, electric, or electronic.

A second edition of AP214 has been issued in 2003, it introduces various corrections, but no change in the scope.

A third edition of AP214 is in preparation, to be harmonized with Object Management Group specifications on PLM services - as well as coming update of AP203 (E2).