DREFs versus XREFs - AutoCAD Tutorial

- [Instructor] Most AutoCAD users are familiar with Xrefs, a way of referencing or linking one drawing's visual information to another drawing. With Civil 3D data, you are able to do something very similar, you are linking one drawing's data to another. Within AutoCAD when you chose to Xref a drawing you could choose which layers you're going to reference into the drawing or better yet when you're creating the source drawing and you add a new layer. You define whether or not you want to share that layer with any drawings that reference that source drawing. So this is kind of the way that Civil 3D works. That way you're not getting the whole drawing, you're not getting all of the data, you just get the information you need. It provides you control over what is actually shared, now more control means more steps. Thus referencing data within Civil 3D starts with choosing to share the data, so we compare Xrefs, one step, you choose which drawing you are going to reference or link. But the drawback is you get everything in the drawing and you have to manage layers regularly and manually. Drefs, which is a shortened phrase for a data reference is a two step process. You have to create the shortcut, in other words you or someone else would have to open the parent drawing. The source drawing, where the data resides, and you have to manually choose to share that data, and in step two is you go to the drawing child, the drawing that is going to reference that data and you have to choose to create a reference of the data that's been shared. So the drawback is it's two steps, the benefit is you get only the data you need to work with, it's cleaner. Now oftentimes, you'll hear the phrase Dref, and data shortcut and ultimately they're referring to the same thing, sharing data. But it's referring to two different steps, one is the choice to share the data. One is to consume or reference that data. Now the reference object, the Dref is read only geometry you can't change the design. This is similar to an Xref, you can't change the Xref without opening that drawing. But with the surface, or whatever else you're referencing, you can apply a local style a style specific to the drawing that it's referenced in. You can apply custom annotation, put specific spot elevations that you don't have in another drawing, run analysis, access the source object's properties and so much more. And obviously, because it's referenced it takes up less file space, so many benefits to using Drefs or data referencing. What though are data shortcuts? Where are they stored? What kind of files are they? Let's talk a little bit about working in data shortcut project folders, and better understand the setup of the directory structure before we begin to share the data, let's look at that next.