# Inventor

This page explains how modifications to parts may affect their persistent ID’s in the Inventor file format.

In most sections below, you will find two tables.

The first set of tables contains two cube images. The left image represents the original, unaltered cube model, while the right image shows the modified instance of the cube model, as described in each section title. The second set of tables provides details on any new or modified persistent ID’s for the model, based on the modified instance described in the section. This includes changes or additions related to faces and edges on the model.

Please note that some sections may not have a second table. However, in these particular cases, context is provided after the initial table.

## Adding a loop to a face - Extruding a hole into a cube

In this instance, the part was modified by adding a loop to a face. This is the same as extruding a hole into the cube.

Original Cube Part | Modified Cube Part
--- | ---

| Faces | Edges
--- | --- | ---
New | 1 face (cylindrical) | 2 edges (see modified image above)
Changes | None | None

## Adding a face to the model - A chamfer

In this instance, the part was modified by adding a face to the model, specifically with a chamfer. A chamfer is a beveled edge that replaces a sharp corner or edge of a part with a sloped surface, typically at a 45-degree angle.

Original Cube Part | Modified Cube Part
--- | ---

| Faces | Edges
--- | --- | ---
New | 1 face | 8 edges (see modified image above) 4 for the chamfer face 4 for the cut edges
Changes | None | 1 edge is removed 4 edges are cut, so the persistent ID will change

## Splitting a face - Adding a groove

In this instance, the part was modified by splitting the a face throughout the model, specifically by adding a uniform groove through the cube, starting from a single face and carrying it through the model’s entirety.

Original Cube Part | Modified Cube Part
--- | ---

| Faces | Edges
--- | --- | ---
New | 3 faces | 14 edges (see modified image above) 10 for the new faces 4 for the cut edges
Changes | 1 face is cut (split) in two. Both have the same persistent ID (see original picture above) | 1 edge is removed 4 edges are cut, so the persistent ID will change

## Splitting a Cylindrical Surface - Adding a hole through a groove

In this instance, the part was modified by splitting a cylindrical surface through the part that has an existing extrusion. Plainly speaking, this is the same as adding a hole through a groove already existing in the part.

Original Cube Part | Modified Cube Part
--- | ---

| Faces | Edges
--- | --- | ---
New | 2 faces, with the same persistent ID (see modified image above) | 4 edges
Changes | None | None

## ID Uniqueness - Hole repetition

More information coming soon

## Editing a feature

In this instance, the part was modified by editing a feature. In this particular example, the cube has been transformed into a rectangule.

Original Cube Part | Modified Cube Part
--- | ---

In the Inventor file format, editing a feature does not change any persistent ID.

## Editing a sketch

In this instance, the part was modified by editing a sketch. In this particular example, the edit was made to the sketch of the cube part model.

Original Cube Part | Modified Cube Part
--- | ---

In the Inventor file format, editing a sketch will have no effect on the persistent ID’s, if the semantic does not change:

> - Editing segment length does not change any persistent ID’s
> - Replacing a segment by a curve will change persistent ID’s as follows:

| Faces | Edges
--- | --- | ---
New | 1 face (see original picture above) | 7 edges
Changes | 1 face is changed | Only 5 edges are kept (see modified image above) Edges of the sketch are changed Projected edges not linked to the curve are kept

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