Now we have a Multi/Sub-Object material that we want to map to the object that has only one texture.
To clean the Checker ID, select the object in
Sub-Object mode and enter 1 in the field ID.

The object does not have any more that one Checker ID but it has the Multi/Sub-Object Material assigned.

In object mode assign the checker material.
Now we see that the material slot Multi/Sub-Object does not have any beveled corners, proving that it is not assigned to the scene any more.

If you use Unwrap UVW, we see that it has only one Checker ID.

Also note that changing the ID does not affect any UVs on the object, fortunately:)

Now we have to crate an of image of our UV.
For that we can capture the UVs Editor screen but you are better of using a small plugin named Texporter as this does a much better job.

Texporter is Freeware and can be downloaded here:

Texporter Web site.

Place it in/Plugins Directory of 3DSmax.
You will find it in the Utils panel, add it in the list with the Sets icon.

It can generate an image of the UV in any size requested, This is great for textures like 2048x1024 by ex:)

To generate the capture of an object, set your requested height and width then click the Pick Object button, followed by selecting the object you need to unwrap.

The top left picture shows the default mode settings for Texporter with filled polygons according to the normals of the object.
The pictures to the top right and opposite, show the adjustments needed for maximum visibility in Photoshop.

Then open the file in Photoshop or any other 2d paint program and check the result by replacing the Checker material with the bitmap texture file.