The information in this article applies to:
When I send a view to a layout in X11 and prior program versions, the following message displays:
What does this mean?
This message is designed to call attention to how layer sets can be assigned to layout views in X11 and prior program versions. If changes are made to a layer set used by a layout view, those changes will affect the appearance of the view on the layout page, even if the change is made while working on an entirely unrelated view in the plan.
Just as in 2D and 3D plan views, all of the objects that display in a layout view are all placed on layers, which can be thought of as a transparency sheet. Nearly all views use multiple layers, like stacks of transparencies put together to show different types of objects. The collection of layer settings for a given view are referred to as a Layer Set, which can be thought of as a stack of transparencies organized to meet a particular need.
There are two approaches to layer sets in prior versions: creating a unique layer set for each layout view and using a task or view-specific layer set for each layout view that was used by the original view.
Creating a unique layer set for each view sent to layout helps many users avoid making unintended changes to views already sent to the layout page. It is helpful in this regard because layout views do not use the layer sets that these users use for drawing. For example, if a user always draws in floor plan view using the Working Layer Set and turns layers on and off in this single layer set as his drawing tasks change, he will not want his layout views to use this same layer set because their appearance will continually change.
The primary disadvantage of this approach is that some users may not realize that although their layout layer sets are unique, they can still be altered. If, for example, you access a plan view by selecting a layout view box and clicking the Open View edit button, the active layer set in that view will be the layout layer set created for that layout view. Any changes made to that layer set will affect the view on the layout page. Another disadvantage to this approach is that it can make the list of layer sets associated with a plan file rather long.
When the Send to Layout 
tool is used to send a view to a layout, a unique layer set can be created by checking the Make Copy of Active Layer Set box in the Send to Layout dialog. By default, this layer set will be assigned the name "Layout Set" followed by a number. If you wish, you can type a New Name for the layer set that reflects what it is used for. Checking this box and proceeding with sending the view to layout will prompt the message that is mentioned at the top of this article.
Other users prefer to use or create custom layer sets for particular drawing tasks and find that the same settings that make for efficient drafting are also appropriate for their printed documents. For example, if a user utilizes the HVAC Layer Set for drawing an HVAC plan, this same layer set can be used when sending the view to a layout. This layer set will not be used unless the user is working on the project's HVAC plan, so the appearance of the HVAC layout views are safe from unintended changes.
When the Send to Layout tool is used, make sure NOT to check the Make Copy of Active Layer Set box if you'd like to use the layer set that's currently in use for the active view.
