diff --git a/winsup/doc/pathnames.sgml b/winsup/doc/pathnames.sgml
index 2daad6d..f501606 100644
--- a/winsup/doc/pathnames.sgml
+++ b/winsup/doc/pathnames.sgml
@@ -510,11 +510,23 @@ displays information such as what model and speed processor you have.
One unique aspect of the Cygwin /proc filesystem
-is /proc/registry, which displays the Windows
-registry with each KEY as a directory and each
-VALUE as a file. As anytime you deal with the
-Windows registry, use caution since changes may result in an unstable
-or broken system. There are additionally subdirectories called
+is /proc/registry, see next section.
+
+
+The Cygwin /proc is not as complete as the
+one in Linux, but it provides significant capabilities. The
+procps package contains several utilities
+that use it.
+
+
+
+The /proc/registry filesystem
+
+The /proc/registry filesystem provides read-only
+access to the Windows registry. It displays each KEY
+as a directory and each VALUE as a file. As anytime
+you deal with the Windows registry, use caution since changes may result
+in an unstable or broken system. There are additionally subdirectories called
/proc/registry32 and /proc/registry64.
They are identical to /proc/registry on 32 bit
host OSes. On 64 bit host OSes, /proc/registry32
@@ -522,10 +534,29 @@ opens the 32 bit processes view on the registry, while
/proc/registry64 opens the 64 bit processes view.
-The Cygwin /proc is not as complete as the
-one in Linux, but it provides significant capabilities. The
-procps package contains several utilities
-that use it.
+Reserved characters ('/', '\', ':', and '%') or reserved names
+(. and ..) are converted by
+percent-encoding:
+
+bash$ regtool list -v '\HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices'
+...
+\DosDevices\C: (REG_BINARY) = cf a8 97 e8 00 08 fe f7
+...
+bash$ cd /proc/registry/HKEY_LOCAL_MACHINE/SYSTEM
+bash$ ls -l MountedDevices
+...
+-r--r----- 1 Admin SYSTEM 12 Dec 10 11:20 %5CDosDevices%5CC%3A
+...
+bash$ od -t x1 MountedDevices/%5CDosDevices%5CC%3A
+0000000 cf a8 97 e8 00 08 fe f7 01 00 00 00
+
+The unnamed (default) value of a key can be accessed using the filename
+@.
+
+
+If a registry key contains a subkey and a value with the same name
+foo, Cygwin displays the subkey as
+foo and the value as foo%val.