AutoCAD 101 Series – External References Week 2 – Details & Commands

xref-0This is the 15th 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 summary of external references basics. <link>.   In this post I will discuss various methods of attaching and accessing external references (XREFS) and common commands and system variables.  In the next post I will go over some XREF-ing tips and tricks.
Because AutoCAD now has so many external attachment options, the “XREF” or EXTERNALREFERENCES” dialogue gives you a full picture of all your attachments.  If you choose the drop down menu in the upper left (Figure A), you will see the variety of file types that can be attached to your working drawing.
Figure A – External file attachment options
For daily use, I use the CLASSICXREF command which is “XR” in my shortcut keys to do daily DWG reference functions, see Figure B.
 Figure B – CLASSICXREF Dialogue
 XREF Binding
 Sometimes you may want to make the externally attached files a permanent part of your working drawing, such as for archiving or sharing with another program that does not understand reference files.  Note that Images, DWFs, and PDFs cannot be bound.
 There are two options for binding external references, ‘Bind’ and ‘Insert’. When choosing the Bind/Bind option all logical named items in the external reference files get bound with a prefix denoting the original XREF name. These items include layers, line types, text styles, blocks, dimension styles, etc.… This can make for a very messy listing of the various types or very useful depending on your goals.  Bind/Insert merges all the items previously mentioned into the working drawing. I typically prefer this binding option as it reduces the clutter in the drawing and makes it easy to do updates.
 Below are some screenshots showing the difference between the Bind/Bind and the Bind/Insert options:
Figure C – Layers before Binding
Figure D – Layers after Bind/Bind
Figure E – Layers after Bind/Insert
As you can see above in Figure E, it is much cleaner to use the Bind/Insert option.  Note that the additional “$0$” symbology will also get added to all your line types, text styles, blocks, etc… when you use the Bind/Bind option.
NOTE: If you are having trouble getting files to bind, run an audit and purge on the XREFS and the working drawing, that typically does the trick.
Overlays vs Attachments
AutoCAD has the ability to ‘nest’ XREFs, i.e. attach an XREF that has an XREF attached to it. In the XREF manager (CLASSICXREF) and in the External References dialogue, you will see two icons representing two different dialogue views. You can see when a XREF is nested using the ‘Tree View’.
 Figure F – List View
Figure G – Tree View
The benefit of this feature is that you can stack XREFs for coordination purposes.  I.E. Assume you are working on a reflected ceiling plan and you need to coordinate diffuser and sprinkler locations with your lights, you can attach the HVAC plan and the sprinkler plan to your file to do your coordination.  You can keep these files attached for future change coordination but hide them from view.  In the “Xref Manager” dialogue, select the file you wish to hide and choose the Unload button.  In the “External References” dialogue, right click the file and select ‘Unload’.  These functions are all part of the normal nesting function of XREF attachments.
There is another attachment option called “Overlay” that allows you to attach a XREF to a file and only allow it to be seen in the current file.  Note that this does not work for Images, DWFs or PDFs.  Using the above example for coordination, if the Electrical designer wishes to power up the lights, they could attach the reflected ceiling plan to their lighting plan to do their circuiting.  If the HVAC plan and the sprinkler plan were standard XREFs, they would see that on their plan as well.  If they have no need for that, to avoid possible confusion you could attach the HVAC and sprinkler plans as “Overlays” and the electrical designer would not even know that they existed.
 You can change the reference type on the fly;  In the “Xref Manager” dialogue, select the file you wish to hide and double-click on the word ‘Attach’ or ‘Overlay’ under Type and it will change. In the “External References dialogue, right click the file and select Attach, and in the pop-up make your change.
Figure H – Xref Manager
Figure I – External References
 Commonly used external Reference Commands
There are a lot of commands and system variables that can be used when using External References, but like most other AutoCAD features you typically only need a few.  Below are the most common commands and SETVARS that you would use on a daily basis.
Edit Reference In-Place
Allows clipping (hiding portions) of the XREF from view. Great for enlarged plans or partial details.(NOTE: for other file types: PDFCLIP, DGNCLIP, IMAGECLIP, DWFCLIP)
Allows binding of individual items from an external DWG file attachment. Say you want to bring in ablock or linetype from the external reference, use XBIND to bind it and then rename it if you would like.
Commonly used external Reference SETVARS
Controls visibility, color, linetype, lineweight, and plot styles. Should be set to “1”.
Controls the dimming for all DWG XREF objects. (Fade from 0 – 90%, user visual preference)
Controls the notification for updated or missing XREFs. Should be set to “1” or “2”.
Controls the default reference type when attaching or overlaying an external reference.  This depends on use, but the majority of XREFs will be “Attachments”, not “Overlays”.  See “Overlays vs Attachments” section above.
 If you are currently using external references then you have already seen the many advantages that they provide.  If you are not currently using external references, it’s about time to get attached!     In the next post I will go over some XREF-ing tips and tricks.
If you run into a snag with any of the topics her or have additional questions, email me at

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