diff --git a/README b/README
index 093280c6fbdc88dfbd21a892c3cbbc9f4dbaf46d..bcce7c5da9b06f3fe8d227d9f3002691990040ba 100644
--- a/README
+++ b/README
@@ -14,11 +14,10 @@
   General Public License terms under which you can copy the files.
 
 * System requirements
-  OpenFOAM is developed and tested on Linux, but should work with other Unix
-  style systems.  To check your system setup, execute the foamSystemCheck script
-  in the bin/ directory of the OpenFOAM installation. If no problems are
-  reported, proceed to "3. Installation"; otherwise contact your system
-  administrator.
+  OpenFOAM is developed and tested on Linux, but should work with other POSIX
+  systems.  To check your system setup, execute the foamSystemCheck script in
+  the bin/ directory of the OpenFOAM installation. If no problems are reported,
+  proceed to "3. Installation"; otherwise contact your system administrator.
 
   If the user wishes to run OpenFOAM in 32/64-bit mode they should consult the
   section "Running OpenFOAM in 32-bit mode".
diff --git a/applications/test/POSIX/Make/files b/applications/test/POSIX/Make/files
new file mode 100644
index 0000000000000000000000000000000000000000..f2f2540e6a8b248b8f80199a293419ec1afec79b
--- /dev/null
+++ b/applications/test/POSIX/Make/files
@@ -0,0 +1,2 @@
+POSIXTest.C
+EXE = $(FOAM_USER_APPBIN)/POSIXTest
diff --git a/applications/test/Unix/Make/options b/applications/test/POSIX/Make/options
similarity index 100%
rename from applications/test/Unix/Make/options
rename to applications/test/POSIX/Make/options
diff --git a/applications/test/Unix/UnixTest.C b/applications/test/POSIX/POSIXTest.C
similarity index 100%
rename from applications/test/Unix/UnixTest.C
rename to applications/test/POSIX/POSIXTest.C
diff --git a/applications/test/Unix/Make/files b/applications/test/Unix/Make/files
deleted file mode 100644
index 6554bfcbb0c4fa955e6b891b285230c2815df207..0000000000000000000000000000000000000000
--- a/applications/test/Unix/Make/files
+++ /dev/null
@@ -1,2 +0,0 @@
-UnixTest.C
-EXE = $(FOAM_USER_APPBIN)/UnixTest
diff --git a/etc/bashrc b/etc/bashrc
index 26dc8c2dfc806109f539bdc8f4e6ae8f5a1b1188..93f2658e45683f04806249142dab2d9806c16abc 100644
--- a/etc/bashrc
+++ b/etc/bashrc
@@ -79,8 +79,8 @@ export WM_THIRD_PARTY_DIR=$WM_PROJECT_INST_DIR/ThirdParty
 
 # Operating System/Platform
 # ~~~~~~~~~~~~~~~~~~~~~~~~~
-# WM_OS = Unix | ????
-: ${WM_OS:=Unix}; export WM_OS
+# WM_OSTYPE = POSIX | ????
+: ${WM_OSTYPE:=POSIX}; export WM_OSTYPE
 
 
 # Compiler: set to Gcc, Gcc43 or Icc (for Intel's icc)
diff --git a/etc/controlDict b/etc/controlDict
index 65058af1a6c6a324f826be3d8b22ec9425195b96..c5f3831a30c143a6b1ee1fabf780c353080e8682 100644
--- a/etc/controlDict
+++ b/etc/controlDict
@@ -195,6 +195,7 @@ DebugSwitches
     PatchToPatchInterpolation 0;
     Phi                 0;
     PointEdgeWave       0;
+    POSIX               0;
     Prandtl             0;
     PrimitivePatch      0;
     Pstream             0;
@@ -249,7 +250,6 @@ DebugSwitches
     ThermoParcel<basicThermoParcel>     0;
     UMIST               0;
     UMISTV              0;
-    Unix                0;
     UpwindFitData<cubicUpwindFitPolynomial> 0;
     UpwindFitData<quadraticLinearUpwindFitPolynomial> 0;
     UpwindFitData<quadraticUpwindFitPolynomial>     0;
diff --git a/etc/cshrc b/etc/cshrc
index f4147422f99595d06db46d35e228a4591146663f..77c432d5dcd7667f550151b7ed5399a36f8d3500 100644
--- a/etc/cshrc
+++ b/etc/cshrc
@@ -73,8 +73,8 @@ setenv WM_THIRD_PARTY_DIR $WM_PROJECT_INST_DIR/ThirdParty
 
 # Operating System/Platform
 # ~~~~~~~~~~~~~~~~~~~~~~~~~
-# WM_OS = Unix | ????
-if ( ! $?WM_OS ) setenv WM_OS Unix
+# WM_OSTYPE = POSIX | ????
+if ( ! $?WM_OSTYPE ) setenv WM_OSTYPE POSIX
 
 
 # Compiler: set to Gcc, Gcc43 or Icc (for Intel's icc)
diff --git a/src/Allwmake b/src/Allwmake
index 3168208c49f2dd8e10c591071fabcb5753e2115a..e374ba62e87a9e7921391501d38eb55dd941c4da 100755
--- a/src/Allwmake
+++ b/src/Allwmake
@@ -6,10 +6,10 @@ set -x
 wmakePrintBuild -check || /bin/rm -f OpenFOAM/Make/$WM_OPTIONS/global.? 2>/dev/null
 
 wmakeLnInclude -f OpenFOAM
-wmakeLnInclude -f OSspecific/$WM_OS
+wmakeLnInclude -f OSspecific/$WM_OSTYPE
 Pstream/Allwmake
 
-wmake libo  OSspecific/$WM_OS
+wmake libo  OSspecific/$WM_OSTYPE
 wmake libso OpenFOAM
 
 wmake libso lagrangian/basic
diff --git a/src/OSspecific/Unix/Make/files b/src/OSspecific/POSIX/Make/files
similarity index 90%
rename from src/OSspecific/Unix/Make/files
rename to src/OSspecific/POSIX/Make/files
index b6e32d80d6652a96636c71d9ae129d35dd89035f..f6e7c2d55eda6f5ffbcc1f0de59451051b45d424 100644
--- a/src/OSspecific/Unix/Make/files
+++ b/src/OSspecific/POSIX/Make/files
@@ -5,14 +5,14 @@ signals/sigQuit.C
 regExp.C
 timer.C
 fileStat.C
-Unix.C
+POSIX.C
 cpuTime/cpuTime.C
 clockTime/clockTime.C
 
-#ifndef SunOS64
-printStack.C
-#else
+#ifdef SunOS64
 dummyPrintStack.C
+#else
+printStack.C
 #endif
 
 LIB = $(FOAM_LIBBIN)/libOSspecific
diff --git a/src/OSspecific/Unix/Make/options b/src/OSspecific/POSIX/Make/options
similarity index 100%
rename from src/OSspecific/Unix/Make/options
rename to src/OSspecific/POSIX/Make/options
diff --git a/src/OSspecific/Unix/Unix.C b/src/OSspecific/POSIX/POSIX.C
similarity index 98%
rename from src/OSspecific/Unix/Unix.C
rename to src/OSspecific/POSIX/POSIX.C
index 9378a21c7caacf345d715be1a1cdc20b6e33a9d1..537cc15caa2d8deddf5ece59b5e09c049e8cd539 100644
--- a/src/OSspecific/Unix/Unix.C
+++ b/src/OSspecific/POSIX/POSIX.C
@@ -23,7 +23,7 @@ License
     Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 
 Description
-    UNIX versions of the functions declared in OSspecific.H
+    POSIX versions of the functions declared in OSspecific.H
 
 \*---------------------------------------------------------------------------*/
 
@@ -32,7 +32,7 @@ Description
 #endif
 
 #include "OSspecific.H"
-#include "Unix.H"
+#include "POSIX.H"
 #include "foamVersion.H"
 #include "fileName.H"
 #include "fileStat.H"
@@ -56,7 +56,7 @@ Description
 
 // * * * * * * * * * * * * * * Static Data Members * * * * * * * * * * * * * //
 
-defineTypeNameAndDebug(Foam::Unix, 0);
+defineTypeNameAndDebug(Foam::POSIX, 0);
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
@@ -536,7 +536,7 @@ Foam::fileNameList Foam::readDir
     // also used as increment if initial size found to be insufficient
     static const int maxNnames = 100;
 
-    if (Unix::debug)
+    if (POSIX::debug)
     {
         Info<< "readDir(const fileName&, const fileType, const bool filtergz)"
             << " : reading directory " << directory << endl;
@@ -557,7 +557,7 @@ Foam::fileNameList Foam::readDir
     {
         dirEntries.setSize(0);
 
-        if (Unix::debug)
+        if (POSIX::debug)
         {
             Info<< "readDir(const fileName&, const fileType, "
                    "const bool filtergz) : cannot open directory "
@@ -690,7 +690,7 @@ bool Foam::cp(const fileName& src, const fileName& dest)
         fileNameList contents = readDir(src, fileName::FILE, false);
         forAll(contents, i)
         {
-            if (Unix::debug)
+            if (POSIX::debug)
             {
                 Info<< "Copying : " << src/contents[i]
                     << " to " << destFile/contents[i] << endl;
@@ -704,7 +704,7 @@ bool Foam::cp(const fileName& src, const fileName& dest)
         fileNameList subdirs = readDir(src, fileName::DIRECTORY);
         forAll(subdirs, i)
         {
-            if (Unix::debug)
+            if (POSIX::debug)
             {
                 Info<< "Copying : " << src/subdirs[i]
                     << " to " << destFile << endl;
@@ -722,7 +722,7 @@ bool Foam::cp(const fileName& src, const fileName& dest)
 // Create a softlink. dst should not exist. Returns true if successful.
 bool Foam::ln(const fileName& src, const fileName& dst)
 {
-    if (Unix::debug)
+    if (POSIX::debug)
     {
         Info<< "Create softlink from : " << src << " to " << dst
             << endl;
@@ -759,7 +759,7 @@ bool Foam::ln(const fileName& src, const fileName& dst)
 // Rename srcFile dstFile
 bool Foam::mv(const fileName& srcFile, const fileName& dstFile)
 {
-    if (Unix::debug)
+    if (POSIX::debug)
     {
         Info<< "Move : " << srcFile << " to " << dstFile << endl;
     }
@@ -784,7 +784,7 @@ bool Foam::mv(const fileName& srcFile, const fileName& dstFile)
 // Remove a file returning true if successful otherwise false
 bool Foam::rm(const fileName& file)
 {
-    if (Unix::debug)
+    if (POSIX::debug)
     {
         Info<< "Removing : " << file << endl;
     }
@@ -804,7 +804,7 @@ bool Foam::rm(const fileName& file)
 // Remove a dirctory and its contents
 bool Foam::rmDir(const fileName& directory)
 {
-    if (Unix::debug)
+    if (POSIX::debug)
     {
         Info<< "rmDir(const fileName&) : "
             << "removing directory " << directory << endl;
diff --git a/src/OSspecific/Unix/Unix.H b/src/OSspecific/POSIX/POSIX.H
similarity index 92%
rename from src/OSspecific/Unix/Unix.H
rename to src/OSspecific/POSIX/POSIX.H
index 97e5d21de2f05d0396d47b7e13baa8202b567f29..fde323b5ffee8158f80292be1c5f67a00b3678ef 100644
--- a/src/OSspecific/Unix/Unix.H
+++ b/src/OSspecific/POSIX/POSIX.H
@@ -23,18 +23,18 @@ License
     Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 
 Namespace
-    Foam::Unix
+    Foam::POSIX
 
 Description
-    UNIX versions of OS-specific functions.
+    OS-specific functions implemented in POSIX.
 
 SourceFiles
-    Unix.C
+    POSIX.C
 
 \*---------------------------------------------------------------------------*/
 
-#ifndef Unix_H
-#define Unix_H
+#ifndef POSIX_H
+#define POSIX_H
 
 #include "className.H"
 
@@ -45,10 +45,10 @@ namespace Foam
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
-namespace Unix
+namespace POSIX
 {
     //- Declare name of the class and its debug switch
-    NamespaceName("Unix");
+    NamespaceName("POSIX");
 }
 
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
diff --git a/src/OSspecific/Unix/clockTime/clockTime.C b/src/OSspecific/POSIX/clockTime/clockTime.C
similarity index 100%
rename from src/OSspecific/Unix/clockTime/clockTime.C
rename to src/OSspecific/POSIX/clockTime/clockTime.C
diff --git a/src/OSspecific/Unix/clockTime/clockTime.H b/src/OSspecific/POSIX/clockTime/clockTime.H
similarity index 100%
rename from src/OSspecific/Unix/clockTime/clockTime.H
rename to src/OSspecific/POSIX/clockTime/clockTime.H
diff --git a/src/OSspecific/Unix/cpuTime/cpuTime.C b/src/OSspecific/POSIX/cpuTime/cpuTime.C
similarity index 100%
rename from src/OSspecific/Unix/cpuTime/cpuTime.C
rename to src/OSspecific/POSIX/cpuTime/cpuTime.C
diff --git a/src/OSspecific/Unix/cpuTime/cpuTime.H b/src/OSspecific/POSIX/cpuTime/cpuTime.H
similarity index 100%
rename from src/OSspecific/Unix/cpuTime/cpuTime.H
rename to src/OSspecific/POSIX/cpuTime/cpuTime.H
diff --git a/src/OSspecific/Unix/dummyPrintStack.C b/src/OSspecific/POSIX/dummyPrintStack.C
similarity index 100%
rename from src/OSspecific/Unix/dummyPrintStack.C
rename to src/OSspecific/POSIX/dummyPrintStack.C
diff --git a/src/OSspecific/Unix/fileStat.C b/src/OSspecific/POSIX/fileStat.C
similarity index 100%
rename from src/OSspecific/Unix/fileStat.C
rename to src/OSspecific/POSIX/fileStat.C
diff --git a/src/OSspecific/Unix/fileStat.H b/src/OSspecific/POSIX/fileStat.H
similarity index 100%
rename from src/OSspecific/Unix/fileStat.H
rename to src/OSspecific/POSIX/fileStat.H
diff --git a/src/OSspecific/Unix/printStack.C b/src/OSspecific/POSIX/printStack.C
similarity index 100%
rename from src/OSspecific/Unix/printStack.C
rename to src/OSspecific/POSIX/printStack.C
diff --git a/src/OSspecific/Unix/regExp.C b/src/OSspecific/POSIX/regExp.C
similarity index 100%
rename from src/OSspecific/Unix/regExp.C
rename to src/OSspecific/POSIX/regExp.C
diff --git a/src/OSspecific/Unix/regExp.H b/src/OSspecific/POSIX/regExp.H
similarity index 100%
rename from src/OSspecific/Unix/regExp.H
rename to src/OSspecific/POSIX/regExp.H
diff --git a/src/OSspecific/Unix/signals/sigFpe.C b/src/OSspecific/POSIX/signals/sigFpe.C
similarity index 100%
rename from src/OSspecific/Unix/signals/sigFpe.C
rename to src/OSspecific/POSIX/signals/sigFpe.C
diff --git a/src/OSspecific/Unix/signals/sigFpe.H b/src/OSspecific/POSIX/signals/sigFpe.H
similarity index 100%
rename from src/OSspecific/Unix/signals/sigFpe.H
rename to src/OSspecific/POSIX/signals/sigFpe.H
diff --git a/src/OSspecific/Unix/signals/sigInt.C b/src/OSspecific/POSIX/signals/sigInt.C
similarity index 100%
rename from src/OSspecific/Unix/signals/sigInt.C
rename to src/OSspecific/POSIX/signals/sigInt.C
diff --git a/src/OSspecific/Unix/signals/sigInt.H b/src/OSspecific/POSIX/signals/sigInt.H
similarity index 100%
rename from src/OSspecific/Unix/signals/sigInt.H
rename to src/OSspecific/POSIX/signals/sigInt.H
diff --git a/src/OSspecific/Unix/signals/sigQuit.C b/src/OSspecific/POSIX/signals/sigQuit.C
similarity index 100%
rename from src/OSspecific/Unix/signals/sigQuit.C
rename to src/OSspecific/POSIX/signals/sigQuit.C
diff --git a/src/OSspecific/Unix/signals/sigQuit.H b/src/OSspecific/POSIX/signals/sigQuit.H
similarity index 100%
rename from src/OSspecific/Unix/signals/sigQuit.H
rename to src/OSspecific/POSIX/signals/sigQuit.H
diff --git a/src/OSspecific/Unix/signals/sigSegv.C b/src/OSspecific/POSIX/signals/sigSegv.C
similarity index 100%
rename from src/OSspecific/Unix/signals/sigSegv.C
rename to src/OSspecific/POSIX/signals/sigSegv.C
diff --git a/src/OSspecific/Unix/signals/sigSegv.H b/src/OSspecific/POSIX/signals/sigSegv.H
similarity index 100%
rename from src/OSspecific/Unix/signals/sigSegv.H
rename to src/OSspecific/POSIX/signals/sigSegv.H
diff --git a/src/OSspecific/Unix/timer.C b/src/OSspecific/POSIX/timer.C
similarity index 100%
rename from src/OSspecific/Unix/timer.C
rename to src/OSspecific/POSIX/timer.C
diff --git a/src/OSspecific/Unix/timer.H b/src/OSspecific/POSIX/timer.H
similarity index 100%
rename from src/OSspecific/Unix/timer.H
rename to src/OSspecific/POSIX/timer.H
diff --git a/src/OpenFOAM/include/OSspecific.H b/src/OpenFOAM/include/OSspecific.H
index e4227879a6a55f17fc35c8464885cade7c554f69..d04243c23dbe9b38fa16d3395da0a5010ce7a1fb 100644
--- a/src/OpenFOAM/include/OSspecific.H
+++ b/src/OpenFOAM/include/OSspecific.H
@@ -26,11 +26,11 @@ InNamespace
     Foam
 
 Description
-    Functions used by OpenFOAM that are specific to the UNIX operating system
-    and need to be replaced or emulated on other systems.
+    Functions used by OpenFOAM that are specific to POSIX compliant
+    operating systems and need to be replaced or emulated on other systems.
 
 SourceFiles
-    Unix.C
+    POSIX.C
 
 \*---------------------------------------------------------------------------*/
 
diff --git a/wmake/Makefile b/wmake/Makefile
index 02c573a2659390c6f644afe3666442eb1692bd54..78b442e43df46b2ec4e517b835504945bf4d0ad4 100644
--- a/wmake/Makefile
+++ b/wmake/Makefile
@@ -63,7 +63,7 @@ CLASSES_DIR        = $(MAKE_DIR)/classes
 SYS_INC            =
 SYS_LIBS           =
 
-PROJECT_INC        = -I$(LIB_SRC)/$(WM_PROJECT)/lnInclude -I$(LIB_SRC)/OSspecific/$(WM_OS)/lnInclude
+PROJECT_INC        = -I$(LIB_SRC)/$(WM_PROJECT)/lnInclude -I$(LIB_SRC)/OSspecific/$(WM_OSTYPE)/lnInclude
 PROJECT_LIBS       = -l$(WM_PROJECT)
 ##
 ## unused: