...
One of the important classes of information that HOOPS Exchange allows you to access from a CAD file is the Product Manufacturing Information (PMI) . These detail the tolerances the which is attached to the 3D model. PMI details the tolerances that a model should be manufactured to. In the past this information was referred to as Geometric Dimensioning and Tolerancing (GD&T) and it was typically done maintained in separate drawings which that were created after associated with the model was designed.
The separation of the manufacturing information from the model meant that manufacturing information had to be generally read by a person which was a barrier to automation. The move to PMI came with this information being Having the manufacturing tolerances associated with the 3D model rather then a separate drawing . This meant a broad range of activities throughout the manufacturing industry being manufacturing processes could be more easily automated. These include the the generation of cost estimates for manufacturing to the validation of parts being machined to required tolerances by CMM machines.
...
In HOOPS Exchange we refer to PMI as Markup. In most cases Markups/PMIs are associated with Views. Views generally consist of a camera, a visibility for different objects in the model (this typically a Part or PMI) and occasionally a cutting plane. You can read more details about Views & Markup in the Markup and Views section of the HOOPS Exchange documentation.
...
When you get to implement PMI support in your application you should start by reading read the Markup and Views section of the HOOPS Exchange documentation. It shows how you would traverse the model tree and then access the PMI-related data-structures in HOOPS Exchange.
...