AutoCAD 101 Series – External References Week 1 – Basics

xref-0Are you new to AutoCAD? Have you been using AutoCAD for years but only use the blocks, styles, layers and tools that others have created?  Do you want to learn more or step up your game on features you’re not very strong in and pick up some practical examples of best practices?  If so, this series is for you.

Over the course of 12 months and maybe more I will cover the basics of a lot of AutoCAD tools and features that many may want or need to learn more about. This is the 14th article in my AutoCAD 101 series – to read about the origination for this series, see the first post here: <Intro>The last post in this series was a wrap-up of all the Block Posts. <link>.

So now we move on to another tool – “External References”.   If you are not using External References (XREFS), which has been around for a long time, you are really missing out on a powerful tool.  If you are a current user keep reading, maybe you will find some new things covered here that you may have been a bit curious about.
Throughout the XREFs posts I will refer to the process of attaching external reference files as “XREF/XREFING”, to the attached files as “XREFS”, and to the drawing that you attach XREFs to as the working drawing.
What are External Reference files (XREFS)?
External references are much like the concept of blocks which was the old school way of handling many of the functions now provided by external references.  Rather than being embedded (inserted) in the file they are externally ‘attached’ or ‘referenced’.  Items that can be attached include; DWGs, PDFs, DGNs, DWFs, and IMAGES (BMP, JPG, TIFF, PNG).  Different commands can be used to attach the various external files, and these commands start with the file type and the word “ATTACH”; PDFATTACH, DGNATTACH, IMAGEATTACH, DWFATTACH.  Or, you can just use the XREF command which will allow you to attach any type from one dialogue.  The individual commands are great for use in automation efforts (Macros, Scripts and Lisp), but will not likely be your first go to option.
Why do you XREF?
Because it is the right thing to do of course! If you are new to AutoCAD and XREFs and wonder what all the fuss is about, XREFs provide a lot of pretty cool features.

  • They keep your working file size small
  • They allow sharing of files while providing real-time updates
  • They are great for coordination
What do you XREF?
As stated above in what are External References, you see a lot of file types that can be attached to your working drawings. Typical items you that would attach include floor plans, title blocks, logos, standard details, survey pictures, and product literature.  But, if you have any of the file types above that you commonly share in projects the options are unlimited. See ‘Figure A’ for the various file types that can be attached in AutoCAD 2015.By choosing the drop down menu in the upper left, next to the DWG with the paperclip, you will see the variety of file types that can be attached to your working drawing.  Because AutoCAD now has so many external attachment options, the “XREF” OR EXTERNALREFERENCES” dialogue gives you a full picture of all your attachments.
Figure A
Why Block Insert when you can XREF?
The big difference between working on a background that is a block verses a background that is an XREF is that the external XREF can be worked on by someone else and be shared real time with multiple users or files.  External references keep your drawing files small and allow you to share the background with multiple drawings.
Example Uses
The following are examples of how XREFs can be used to increase your productivity. The one big advantage that every one of these examples is that when you update the XREF every file that references it is updated.
Title Blocks
This is probably one of the top two uses of external references. In a typical project the one item that is common among all drawings is the title block.  By XREFing the title block drawing you can make changes to the address, issue date, customer info, and logo in one place and have all of your working drawings updated automatically.
Note that the logo in the title block is another common XREF (IMAGEATTACH). You can also enter all your revision info for the entire job in this drawing as individual layers. I. E. REV-1, REV-2, etc… freeze them in the title block and thaw as necessary in the working drawings.
Floor plans
Probably the top use of XREFs.  Through a combination of external references, clipping, and paper space, you can attach multiple plans and plot at different scales all on one sheet.
XREF’s can be renamed when attached, and by doing this you can attach the same file multiple times and control the visual aspects of each as if it were a separate file.  This is referred to as logical name versus the actual name. An example would be attaching a floor plan (FP-1) that has demo and new work layers all in one drawing.  By attaching FP-1 and then renaming it in the XREF dialogue to FP-Demo you can freeze and thaw layers as required to show the demo portion of the plan. You then attach (not copy) the FP-1 plan again and freeze and thaw layers as required to show new work.  Since each logical XREF has its own layer structure showing up in your layer dialog you can also change colors and line types.
Note that this feature relies on your VISRETAIN SETVAR being set to “1 “.
Product literature
In some jurisdictions it is required manufacturers data, safety information, or product performance, is shown on the drawings. Instead of retyping all this data or redrawing it (or creating sticky backs for you old-timers) just XREF the PDF or image files into your working drawings.
Standard details
Nearly every set of drawings utilizes some form of standard details. You could have a standard detail sheet with the details XREFed so that the sheet is always up-to-date.  If you need to revise a standard detail to be job specific or freeze the details specifics from changing during the course of the job, you can bind those details into your working drawing and edit as required with in the current job.
Survey information
When doing renovation projects, a necessary task is to provide enough information on the existing conditions to allow contractors to be able to see what they face so they can give an accurate bid.  Although requiring a field visit is always a good idea that is not always practical for some projects.  A great way to enhance your drawings is to IMAGEATTACH field photos in your drawings and add notes detailing the specifics.
Key plans
When working on large building projects or campus wide projects, you can attach aerial views or screenshots from your favorite mapping program to visually show your site or campus.  For the large building projects you can attach a drawing at a reduced scale of the overall building with hatched areas or layers frozen or thawed to represent specific areas of work.  Any plan changes will automatically update your key plan as the project progresses.
These are just some of the uses for external references.  Your imagination can open up many more.
In the upcoming posts I will cover commands and settings that are important and useful for utilizing XREFs efficiently.
If you run into a snag with any of the topics her or have additional questions, email me at

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