[00:00] In this lesson we'll talk about Reference Tags. So a Reference Tag is another Tag that pulls its value from a source Tag. So there's some other tag in the system that the Reference Tag is referencing. So we see here I have an OPC Tag. And maybe in some cases I don't want to use the OPC Tag in bindings on some of my Windows, or maybe in some of my Views. Maybe because the tag path might change as I'm actively developing. So one of the things you can do is you can come over to the Tag Browser, you can hit the Add Tag dropdown and under New Standard Tag we can select a Reference Tag. So we'll give it a name here just so we can keep the two apart. And a Reference Tag needs a Source tag path defined. So we have to point this Reference Tag to another Tag in the system somewhere. So I'll hit the Edit button here. I'll go up to my Tags folder here and I'll grab my Setpoint tag, hit Commit. Now that we're all set here, we'll hit OK. So we can see our Reference Tag. Now the way this works is that if my source Tag here changes value, and I enable Read/Write Mode here, you'll see the write goes to the Setpoint tag and Reference Tag updates as well. And of course if I change the value on the Reference Tag, it writes back to the source Tag, which is my Setpoint Tag in this case. And this Reference Tag, for all intents and purposes, is just another Tag in the system. So if I double-click on it we can look at the settings again. I can scroll down and we have the familiar Scripting, Alarms, security, and history. So we can apply all the same settings to a Reference Tag that we could an OPC Tag. I'm going to close this here, and of course I can drag and drop this tag onto my Window here or onto a View, and it works just the same. So of course as I'm building and I'm placing components on the screen, if my Setpoint tag, that's coming from my PLC, say I need to move it into another folder to restructure my tag provider, of course that breaks the paths for all my components. Any Tag Bindings I was using, well they're looking at an incorrect path now. So instead of going and updating every single component, I could just redirect my Reference Tag and point it to the new location of the source Tag. So if we double-click again we can take a look again at the Source Tag Path property, hit the little Edit button here. We'll go to our Tower 1 here, grab the set point, Commit, and hit OK. And that one is fine again, whereas my original component, I would have to actually rebind. And of course I'd have to rebind any other components that were directed or pointed at my Setpoint Tag. And of course for the Reference Tag here you can set the Source Tag Path to a Memory Tag or other types of Tags. So if you're trying to develop a project and you don't have access to their PLC program, but you have an idea of what kind of Tags they have, you could just create a bunch of Memory Tags, add a bunch of Reference Tags, and then when you're deploying the project live in the system, replace the Memory Tags with OPC Tags and update your Reference Tags, that way you don't have to touch any of your screens at all. So again, the Reference Tag, it's very simplistic in what it does, but it does provide you a way to sort of separate the source value from an OPC address, versus the tag configuration in Ignition.