How can I turn off multiple windows in a drawing?

[abuv_all]

Is there a system variable for turning off the ability to have multiple drawings opened in one autocad session? I have a co-worker that wants his autocad to only be able to open one drawing at a time. He is currently using plain autocad 2008. Thanks

[bcgatti]

Take a look a the SDI system variable. If it is set to 1 it will open one file per session.

[jpaulsen]

Changing the setting of SDI will have adverse affects on some commands. I don;t have the software in front of me to check but I believe the Reference Manager is one that will no longer work.

[abuv_all]

Changing the setting of SDI will have adverse affects on some commands. I don;t have the software in front of me to check but I believe the Reference Manager is one that will no longer work.

Well, for the meantime it seems like this will work. I'm not sure how much AutoCAD this co-worker uses, so if doesn't affect the basic commands.. I think he should be ok. Thanks for both of your help.