I'm trying to complete de guide "Create a Custom Asset Viewer". In this guide I have to use PTC.DeveloperProgram model tag but this model tag is missing in my thingworx platform local installation (platform 8.4.5).
The supporting files are located here, but I'm not seeing the import procedure anywhere in the guide. The model tag is included in PTC.DeveloperProgram.CustomAssetViewer_8.4.zip. You could extract that one entity for import, but I'm not sure what other issues you may run into.
I have reached out to the author of this content to request an update.
In the meantime, please let me know if you have further questions.