Loosely speaking, in AutoCAD, XREF is the command that helps embed a file to the current drawing. The XREF command allows to attach files such as raster images, DWG, DWF, Microstation DGN files and more.
DWG (from DraWinG)
DWF (Drawing Web Format)
An xref is a reference to an external file, that appears in the current drawing and gives you the visual impression that it is part of the drawing.
Xrefs are often compared to blocks, but they have a major advantage over the latter. When a block is inserted into a project, its geometry does not change regardless of the source file’s changes. When an Xref is inserted to a projects, the host project is updated at every opening with what the current state of the xref is.
Let’s say, I have just xrefed a DWG project my colleague is working on, every time I open or intentionally update the xrefs, I will have the last saved version of the content of his files.
Another Advantages of xref is that its content is not stored in your drawing, it just acts like a pointer that returns the images of the seed file without eating any space.
When the project you are working on have some xrefed files, you will see the following tools in your status bar.
How to xref in AutoCAD
To attach an external reference to your drawing in AutoCAD, you need to
Make sure you are on the appropriate layer where you want the external reference to be, Type XREF and press Enter
Click on the icon shown on the previous image.
Browse your computer (or your network) and select the file you want to attach
Specify the parameters in the window below.
You can use this window to set an insertion point, Scale the object you are going to included, rotate it.
This feature just tells AutoCAD what to do with overall project. If we set this to Attachment, if someone else xrefs our drawing, he will also see files that are xrefed to it, but if we set this to Overlay, that someone else wont be able to see files xrefed to our drawing if he does actually xref our drawing.
The path type simply tells AutoCAD how it will index the source file of the reference object.
It is recommended to use the Full Path option while attaching files to your drawing, this option will store the path to the files, and AutoCAD will always find the xrefed files as long as its location does not change on your computer or network.
As for No path, When using it, AutoCAD will actually store only the name of the xrefed files, and this works best when all xrefed files are located in the same folder with the host drawing.
Xrefing file types
You can attach files of other types.
Xref is a very important tools while working on a team project in AutoCAD, and remember you can always hide, unload, load back, Detach files from your drawings.