Autodesk 235B1-05A761-1301 User Guide - Page 177

Whenever you open a drawing, the software reloads the xref drawings attached to it so that changes made to the xref drawings are reflected in your building system drawing. For example, if you attach an architectural floor plan as an xref, and the architect subsequently changes the location of the building's mechanical room, the changes to the architectural floor plan are automatically reflected in your building systems drawing the next time that you open it. You can also reload xrefs on demand and check for interferences between building system objects and structural members by applying interference detection highlighting to your drawing. There are 2 types of xrefs: attachment and overlay. Unlike an attached xref, an overlaid xref is not displayed when the drawing is itself attached or overlaid as an xref to another drawing-a process referred to as nesting xrefs. Overlaid xrefs are designed for data sharing in a network environment. By overlaying an xref, you can see how your drawing relates to the drawings of other groups without changing your drawing by attaching an xref. Changes made to an xref drawing, whether attached or overlaid, are displayed in your drawing when you open the drawing or reload the xref. Linking xrefs to your drawings is effective when creating design drawings and construction documents. Design projects typically involve the coordination of many drawings, and sharing the content of those drawings is fundamental to efficient project management. Establishing standards for using xrefs helps you to use drawings optimally and minimize the need to re-create drawing content. The following cite several advantages to using xrefs in AutoCAD MEP drawings: ■ You can reference an architectural drawing as a base for your mechanical, electrical, or plumbing drawings. In addition, you are aware immediately of any changes to the architectural drawing because the changes are reflected when you open your drawing or reload the xref. ■ You can assemble master drawings from individual design drawings. For example, several people can work with different sections of a design for a large building (such as by floor or by wing), and the individual designs can be referenced into a master drawing. ■ You can attach drawings containing borders, title blocks, and other office standards for plotting as xrefs for easy maintenance. ■ You can choose not to load an xref if you do not need it as a reference. The xref does not use system resources when it is not loaded. NOTE See Concepts of Drawing Management in the AutoCAD Architecture Help and "Reference Other Drawing Files" in AutoCAD Help. Attaching or Overlaying Xrefs Xrefs enable you to begin with a drawing that contains walls and other spatial elements that you need, such as a floor plan, reflected ceiling plan, or AutoCAD Architecture building model. NOTE In a Drawing Management project, attach xrefs using the Project Navigator only. For more information, see Concepts of Drawing Management in the AutoCAD Architecture Help. If you attach or overlay an xref created in a previous version of the software, the file format of the xref is not updated to the current version (which would make the xref incompatible with the version in which it Attaching or Overlaying Xrefs | 159