Hey folks, Phil Zito here and welcome back. In this post, we're going to be discussing what is an open building automation system. This topic has been getting a lot of noise lately on social media and on YouTube. So, I wanted to revisit an article we wrote a while ago about how to evaluate a building automation system where we go through what an open building automation system is and what are the types of openness in building automation systems. We're going to go through some criteria related to how to evaluate each type of openness and we're going to go through some spec language that you can utilize if you're a specifier, contractor, or an owner.