Hi Alex,
Thanks for your interest in Alibre's STEP Schema. However, at this point, we have not made this available to any external developers.
We would be interested in knowing what project you have in mind which wants you to use the Step Schema rather than the API?
We strongly recommend you to rely on our API and future improvements to the API we make, because, if you have to use the Step Schema, it will be lot harder as you have to interpret the schema and map it to your understanding. Since there are several objects in our schema, more programming effort and several technical challenges would be involved.
Please let us know if you have any further questions on this.
Thanks,
Shubha,
Alibre, Inc.