Part 7
Module 35: Reference Files
Learning Outcomes
When you have completed this module, you will be able to:
- Describe reference files and explain how they are used in an AutoCAD drawing.
- Apply the XREF command.
Reference Files
An external reference file is a drawing file linked to the current drawing. It acts as one object similar to a block and appears to be part of the current drawing. Usually called a reference file or a xref, it is quite different from a block. A reference file updates itself whenever the drawing it is linked to is opened. It can also be updated manually by the CAD operator. If the drawing that is attached as an xref is changed, the changes will appear when the drawing it is attached to is opened or reloaded. Since it is only linked to the drawing, it does not add a significant amount of data to the drawing’s database.
The XREF command is used to manage the reference files that are linked to the current drawing. You can attach more than one reference file at the same time. All objects in the reference file must be in Model space. Reference files can be scaled or rotated when they are attached with the XREF command or after they are attached with the SCALE and/or ROTATE commands. You can snap to the object snap modes of objects in the reference files. A reference file can be edited in the current drawing with the changes going back to the original drawing file. This is done with the REFEDIT command.
Xref Dependant Named Objects
Xref dependent named objects are the layers, linetypes, dimension styles, blocks, and text styles of the reference file. They are added to the drawing they are attached to as non-graphical object information. The names are changed so that no two names are the same. Table 35-1 shows how the non-graphical names are dealt with by AutoCAD.
This table demonstrates how AutoCAD names the xref dependent named objects for layers, linetypes, dimension styles, blocks, and text styles. In this table, the name of the attached xref file drawing is House Plan and a layer in that drawing is First Floor and a block named Coffee Table. For a reference file, the name of the non-graphical object is changed to the name ‘ drawing name|object ‘. If it is bound to the drawing, it is renamed ‘ name$n$objectname ‘. The ‘ n ‘ starts with zero and increases by one if the same name is encountered.
Binding a Reference File
A reference file can be bound to the current drawing it is attached to with the XREF command. When a reference drawing is bound to the drawing, the XREF command converts it into a block. The xref dependent named objects are renamed according to Table 35-1. A block can be exploded to convert the objects into single objects and they become part of the drawing. When a reference file is bound, it can either be bound or inserted. Inserting a reference file converts it into a block but it strips the named non-graphical objects back to their original names. See Table 35-1
AutoCAD Command: XREF
The XREF command is us