2013

Table Of Contents
Resolve Circular External References
If a referenced drawing contains a sequence of nested references that refers
back to itself, an error message is displayed.
A drawing that contains a sequence of nested references that refers back to
itself is considered a circular reference. For example, if drawing A attaches
drawing B, which attaches drawing C, which attaches drawing A, the reference
sequence A>B>C>A is a circular reference.
If the program detects a circular reference while attaching an xref, a warning
is displayed asking you if you want to continue. If you respond with yes, the
program reads in the xref and any nested xrefs to the point where it detects
the circularity. If you respond with no, the process is halted and the xref is
not attached.
If a circular reference is encountered while loading a drawing, an error message
is displayed and the circular reference for the current session is broken. For
example, if you have the circular reference A>B>C>A, and you open a.dwg,
the program detects and breaks the circularity between c.dwg and a.dwg. The
following error message is displayed:
Breaking circular reference from C to current drawing.
Resolve Name Conflicts in External References
When you attach an xref, the names of its blocks, dimension styles, layers,
linetypes, and text styles are differentiated from those in the current drawing.
A typical xref definition includes objects, such as lines or arcs. It also includes
xref-dependent definitions of blocks, dimension styles, layers, linetypes, and
text styles. When you attach an xref, the program differentiates the names of
these xref-dependent named objects from those in the current drawing by
preceding their names with the name of the referenced drawing and a vertical
bar character ( | ). For example, the xref-dependent named object that is a
layer named STEEL in a referenced drawing called stair.dwg is listed as
STAIR|STEEL.
When you attach an xref, the definitions of its dependent named objects are
not added to your drawing permanently. Instead, these definitions are loaded
from the referenced drawing file each time you reload it.
662 | Chapter 11 Share Data Between Files