Index: Makefile
==================================================================
--- Makefile
+++ Makefile
@@ -1,6 +1,6 @@
-CPPFLAGS := -I. -DUSE_TCL_STUBS=1 -DXVFS_MODE=standalone
+CPPFLAGS := -I. -DUSE_TCL_STUBS=1 -DXVFS_MODE_STANDALONE
 CFLAGS   := -fPIC -g3 -ggdb3 -Wall
 LDFLAGS  :=
 LIBS     := -ltclstub8.6
 
 all: example.so

Index: xvfs-core.c
==================================================================
--- xvfs-core.c
+++ xvfs-core.c
@@ -1,9 +1,10 @@
 #include <xvfs-core.h>
 #include <string.h>
 #include <tcl.h>
 
+#if defined(XVFS_MODE_SERVER) || defined(XVFS_MODE_STANDALONE) || defined(XVFS_MODE_FLEXIBLE)
 #define XVFS_ROOT_MOUNTPOINT "//xvfs:/"
 
 struct xvfs_tclfs_instance_info {
 	struct Xvfs_FSInfo *fsInfo;
 	Tcl_Obj            *mountpoint;
@@ -74,12 +75,13 @@
 	pathStr = xvfs_relativePath(path, instanceInfo);
 fprintf(stderr, "Called open(%s)!\n", pathStr);
 	
 	return(NULL);
 }
+#endif /* XVFS_MODE_SERVER || XVFS_MODE_STANDALONE || XVFS_MODE_FLEIXBLE */
 
-#if XVFS_MODE == standalone
+#if defined(XVFS_MODE_STANDALONE)
 /*
  * Tcl_Filesystem handlers for the standalone implementation
  */
 static struct xvfs_tclfs_instance_info xvfs_tclfs_standalone_info;
 static int xvfs_tclfs_standalone_pathInFilesystem(Tcl_Obj *path, ClientData *dataPtr) {
@@ -141,11 +143,11 @@
 			Tcl_SetResult(interp, "Unable to allocate Tcl_Filesystem object", NULL);
 		}
 		return(TCL_ERROR);
 	}
 	
-	xvfs_tclfs_Info->typeName                   = strdup("xvfs");
+	xvfs_tclfs_Info->typeName                   = "xvfs";
 	xvfs_tclfs_Info->structureLength            = sizeof(*xvfs_tclfs_Info);
 	xvfs_tclfs_Info->version                    = TCL_FILESYSTEM_VERSION_1;
 	xvfs_tclfs_Info->pathInFilesystemProc       = xvfs_tclfs_standalone_pathInFilesystem;
 	xvfs_tclfs_Info->dupInternalRepProc         = NULL;
 	xvfs_tclfs_Info->freeInternalRepProc        = NULL;
@@ -188,10 +190,12 @@
 		return(tcl_ret);
 	}
 	
 	return(TCL_OK);
 }
-#else
+#endif
+
+#if defined(XVFS_MODE_SERVER)
 int Xvfs_Register(Tcl_Interp *interp, struct Xvfs_FSInfo *fsInfo) {
 	return(TCL_ERROR);
 }
 #endif

Index: xvfs-core.h
==================================================================
--- xvfs-core.h
+++ xvfs-core.h
@@ -1,7 +1,7 @@
-#ifndef XVFS_COMMON_H_1B4B28D60EBAA11D5FF85642FA7CA22C29E8E817
-#define XVFS_COMMON_H_1B4B28D60EBAA11D5FF85642FA7CA22C29E8E817 1
+#ifndef XVFS_CORE_H_1B4B28D60EBAA11D5FF85642FA7CA22C29E8E817
+#define XVFS_CORE_H_1B4B28D60EBAA11D5FF85642FA7CA22C29E8E817 1
 
 #include <tcl.h>
 
 #define XVFS_PROTOCOL_VERSION 1
 
@@ -15,12 +15,48 @@
 	xvfs_proc_getChildren_t  getChildrenProc;
 	xvfs_proc_getData_t      getDataProc;
 	xvfs_proc_getInfo_t      getInfoProc;
 };
 
-#if XVFS_MODE == standalone
-#define Xvfs_Register(interp, fsInfo) xvfs_standalone_register(interp, fsInfo)
+#define XVFS_REGISTER_INTERFACE(name) int name(Tcl_Interp *interp, struct Xvfs_FSInfo *fsInfo);
+
+#if defined(XVFS_MODE_STANDALONE)
+/*
+ * In standalone mode, we just redefine calls to
+ * Xvfs_Register() to go to the xvfs_standalone_register()
+ * function
+ */
+#  define Xvfs_Register xvfs_standalone_register
+XVFS_REGISTER_INTERFACE(Xvfs_Register)
+
+#elif defined(XVFS_MODE_FLEXIBLE)
+/*
+ * In flexible mode we declare an external symbol named
+ * Xvfs_Register(), as well as an internal symbol called
+ * xvfs_flexible_register(), which we redefine future
+ * calls to Xvfs_Register() to invoke
+ */
+extern XVFS_REGISTER_INTERFACE(Xvfs_Register)
+#  define Xvfs_Register xvfs_flexible_register
+XVFS_REGISTER_INTERFACE(Xvfs_Register)
+
+#elif defined(XVFS_MODE_CLIENT)
+/*
+ * In client mode we declare an external symbol named
+ * Xvfs_Register() that must be provided by the environment
+ * we are loaded into
+ */
+extern XVFS_REGISTER_INTERFACE(Xvfs_Register)
+
+#elif defined(XVFS_MODE_SERVER)
+/*
+ * In server mode we are going to implementing Xvfs_Register()
+ * for flexible/client modes, just forward declare it
+ */
+XVFS_REGISTER_INTERFACE(Xvfs_Register)
+
+#else
+#  error Unsupported XVFS_MODE
 #endif
 
-int Xvfs_Register(Tcl_Interp *interp, struct Xvfs_FSInfo *fsInfo);
 
 #endif