Look more closely at the three options in Tools > Options > Open and
Save > External References. The three options are for XLOADCTL
are:
0 Disabled
1 Enabled
2 Enabled with Copy
Setting XLOADCTL to 2 (Enabled with copy) is the not the best choice,
there's more to the story to understand the best option. Setting XLOADCTL
off or to 0 (Disabled) has exactly the effect you want, allowing XREFs to be
currently attached, yet other people can still open and edit an xref
concurrently... basically this setting makes XREFs behave the way they did
pre-Release 14.
Enabled with Copy is a boondoggle in my opinion, because of the following
reasons:
1. It's unnecessary, because just turning it off gives the editable
XREF state you're looking for.
2. Enabled with Copy is intended to work with Layer and Spatial
Indexing turned on using the INDEXCTL system variable (read HELP, it explains
more about what the intent is).
INDEXCTL controls whether layer and spatial
indexes are created and saved in drawing files.
0 No
indexes are created
1 Layer index is
created
2 Spatial index is
created
3 Layer and spatial indexes are created
The purpose of this concept is to potentially gain faster loads on
DWGs/XREFs that are clipped, so that AutoCAD only loads what it needs. In
my tests of this with the first couple of releases that had this command, is
that in day to day practicle purposes in our line of work, there were no
significant gains trying to use this. DWG files get larger in size with
INDEXCTL turned on all the way, as it has lots more information to store within
the DWG.
3. Enabled with Copy, it means exactly what it implies, it copies all
of your XREFs and Overlays to a temporary file location defined by the XLOADPATH
system variable, and it does this EACH TIME THE DRAWING IS OPENED. So
imagine the impact to a network, and people have AutoCAD drawings that each have
10 XREFs totalling 20 MB worth of XREFs. Everytime a parent DWG is opened,
it has to copy over 20 MB worth of XREFs to a temporary location, then opens the
copied versions of the XREFs... that's a huge amount of overhead and network
traffic, when in fact turning XLOADCTL off works just fine without all of these
gymnastics. If you open the parent DWG 10 times, then it will have copied
those 20 MB worth of XREFs to the temp folder 10 times... such unnecessary
overhead. The AutoCAD Help tells you to use Enable with Copy, so it too is
misleading, perhaps why the pat answer seen in these NGs to use the third option
Enable with Copy.
4. If Enable with Copy is used, if you crash, the temporarily copied
XREF files get left behind... more file management.
So, unless there is some compelling results that you can get demandloading
drawings using not only using XLOADCTL=2 but also its partner
INDEXCTL=1,2, or 3 for which you see a real speed increase, I don't think it's
worth taking that route.