diff --git a/collects/framework/private/dir-chars.rkt b/collects/framework/private/dir-chars.rkt
index 2c75ae7..e5e195c 100644
--- a/collects/framework/private/dir-chars.rkt
+++ b/collects/framework/private/dir-chars.rkt
@@ -1,6 +1,7 @@
 #lang racket/base
 (require racket/list)
 (provide adjustable-chars
+         double-barred-chars
          up-chars
          dn-chars
          lt-chars
@@ -36,4 +37,8 @@
 
 (define adjustable-chars
   (remove-duplicates
-   (append up-chars dn-chars lt-chars rt-chars)))
\ No newline at end of file
+   (append up-chars dn-chars lt-chars rt-chars)))
+
+(define double-barred-chars
+  (remove* '(#\+ #\- #\|) 
+           adjustable-chars))
\ No newline at end of file