Deployments of Provider Backbone Bridging (PBB)

Hello folks, Based on data I've gathered through quantitative and qualitative surveying, I can detect no application of Provider Backbone Bridging (MAC-in-MAC). Please bear with me while I clarify that I am not enquiring about Provider Bridging (QinQ). I would like to ask specifically about knowledge of deployments of PBB. If anyone would care to share data points, on- or off-list, I would love to know about them. I am open to anything on the subject of PBB's adoption that you are free to share with me. I am bound by GDPR and will anonymize any data that is not open for public disclosure. Thank you! Etienne -- Ing. Etienne-Victor Depasquale