diff --git a/configure/CONFIG b/configure/CONFIG
index c3ba9ee5f..68d15aa9f 100644
--- a/configure/CONFIG
+++ b/configure/CONFIG
@@ -64,14 +64,14 @@ endif
 # --------
 #  Build client objects statically ?  must be either YES or NO
 #STATIC_BUILD=NO
-#  Unix Optimization,   must be either YES or NO
-#HOST_OPT=YES
-#  Cross builds Optimization,  must be either YES or NO
-#CROSS_OPT=YES
+#  Host build optimization,   must be either YES or NO
+#Host_OPT=YES
+#  Ioc build optimization,  must be either YES or NO
+#Ioc_OPT=YES
 #  Generate Verbose Compiler Warnings for host build,  must be either YES or NO
-#HOST_WARN=YES
-#  Generate Verbose Compiler Warnings for cross builds,  must be either YES or NO
-#CROSS_WARN=YES
+#Host_WARN=YES
+#  Generate Verbose Compiler Warnings for ioc builds,  must be either YES or NO
+#Ioc_WARN=YES
 #etc.
 
 #CROSS_COMPILER_TARGET_ARCHS=mv167
diff --git a/configure/CONFIG_COMMON b/configure/CONFIG_COMMON
index 4bef6228d..37159c047 100644
--- a/configure/CONFIG_COMMON
+++ b/configure/CONFIG_COMMON
@@ -7,13 +7,14 @@
 #
 
 #-------------------------------------------------------
-# Default valid build types and include directory suffixes
+# Common build type definitions
 #
 # Host means single-thread non-ioc
 # HostMT means multi-thread non-ioc
 # Ioc means multi-thread ioc
 # IocST means single-thread ioc
 
+# Default valid build types and include directory suffixes
 VALID_BUILDS = Host Ioc HostMT IocST
 Host_SUFFIX=
 HostMT_SUFFIX=MT
@@ -26,14 +27,13 @@ B_T_SUFFIX = $($(B_T)_SUFFIX)
 OS_SRC_DIRS += $(foreach dir,$(SRC_DIRS), \
             $(dir)/os/$(OS_CLASS)$(B_T_SUFFIX) $(dir)/os/posix$(B_T_SUFFIX) \
             $(dir)/os/$(OS_CLASS) $(dir)/os/posix \
-            $(dir)/generic$(B_T_SUFFIX) $(dir)/generic $(dir))
-
-OS_DIRS += ../os/$(OS_CLASS)$(B_T_SUFFIX) ../os/posix$(B_T_SUFFIX) \
-           ../os/$(OS_CLASS) ../os/posix \
-           ../generic$(B_T_SUFFIX) ../generic 
+            $(dir)/generic$(B_T_SUFFIX) $(dir)/generic $(dir)) \
+            ../os/$(OS_CLASS)$(B_T_SUFFIX) ../os/posix$(B_T_SUFFIX) \
+            ../os/$(OS_CLASS) ../os/posix \
+            ../generic$(B_T_SUFFIX) ../generic 
 
 # compile line include directories
-SRC_INCLUDES += $(addprefix -I,$(OS_SRC_DIRS) $(OS_DIRS))
+SRC_INCLUDES += $(addprefix -I,$(OS_SRC_DIRS))
 INSTALL_INCLUDES += \
        -I$(INSTALL_INCLUDE)/os/$(OS_CLASS)$(B_T_SUFFIX) \
        -I$(INSTALL_INCLUDE)/os/posix$(B_T_SUFFIX) \
@@ -212,13 +212,13 @@ INSTALL_DBDFLAGS = -I $(INSTALL_LOCATION)/dbd
 
 #--------------------------------------------------
 # Warnings flags  (CONFIG.<arch> will override)
-WARN_CFLAGS = $($(ANSI)_WARN_$($(BUILD_CLASS)_WARN))
-WARN_CXXFLAGS = $($(CPLUSPLUS)_WARN_$($(BUILD_CLASS)_WARN))
+WARN_CFLAGS = $($(ANSI)_WARN_$($(B_T)_WARN))
+WARN_CXXFLAGS = $($(CPLUSPLUS)_WARN_$($(B_T)_WARN))
 
 #--------------------------------------------------
 # Optimization flags  (CONFIG.<arch> will override)
-OPT_CFLAGS = $($(ANSI)_OPT_$($(BUILD_CLASS)_OPT))
-OPT_CXXFLAGS = $($(CPLUSPLUS)_OPT_$($(BUILD_CLASS)_OPT))
+OPT_CFLAGS = $($(ANSI)_OPT_$($(B_T)_OPT))
+OPT_CXXFLAGS = $($(CPLUSPLUS)_OPT_$($(B_T)_OPT))
 OPT_LDFLAGS =
 
 #--------------------------------------------------
diff --git a/configure/CONFIG_SITE b/configure/CONFIG_SITE
index ddac1a402..14aa35ff4 100644
--- a/configure/CONFIG_SITE
+++ b/configure/CONFIG_SITE
@@ -99,14 +99,14 @@ STATIC_BUILD=NO
 #	must be either YES or NO
 Host_OPT=YES
 
-#  IOC build optimization
+#  Ioc build optimization
 #	must be either YES or NO
-IOC_OPT=YES
+Ioc_OPT=YES
 
 #  Generate Verbose Compiler Warnings for Host builds
 #	must be either YES or NO
 Host_WARN=YES
 
-#  Generate Verbose Compiler Warnings for IOC builds
+#  Generate Verbose Compiler Warnings for Ioc builds
 #	must be either YES or NO
-IOC_WARN=YES
+Ioc_WARN=YES
diff --git a/configure/RULES_BUILD b/configure/RULES_BUILD
index 51b3f4bb5..5c5016c33 100644
--- a/configure/RULES_BUILD
+++ b/configure/RULES_BUILD
@@ -32,19 +32,11 @@
 ifdef T_A
 ifdef B_T
 
-ifneq ($(strip $(SRC_DIRS)),)
-vpath %.c $(USER_VPATH) . .. $(OS_SRC_DIRS)
-vpath %.cc $(USER_VPATH) . .. $(OS_SRC_DIRS)
-vpath %.C $(USER_VPATH) . .. $(OS_SRC_DIRS)
-vpath %.rc $(USER_VPATH) . .. $(OS_SRC_DIRS)
-vpath %.h $(USER_VPATH) . .. $(OS_SRC_DIRS)
-else
-vpath %.c $(USER_VPATH) . .. $(OS_DIRS)
-vpath %.cc $(USER_VPATH) . .. $(OS_DIRS)
-vpath %.C $(USER_VPATH) . .. $(OS_DIRS)
-vpath %.rc $(USER_VPATH) . .. $(OS_DIRS)
-vpath %.h $(USER_VPATH) . .. 
-endif
+vpath %.c $(USER_VPATH) $(OS_SRC_DIRS) .. .
+vpath %.cc $(USER_VPATH) $(OS_SRC_DIRS) .. .
+vpath %.C $(USER_VPATH) $(OS_SRC_DIRS) .. .
+vpath %.rc $(USER_VPATH)$(OS_SRC_DIRS) .. .
+vpath %.h $(USER_VPATH) $(SRC_DIRS) .. .
 #	This prevents base/src/include/*.h from being installed. Why??
 #vpath %.h ../os/$(OS_CLASS)
 
@@ -308,21 +300,9 @@ INSTALL_INC += $(foreach inc,$(INC), \
          $(dir)/os/posix/$(inc) \
          $(dir)/generic$(B_T_SUFFIX)/$(inc) \
          $(dir)/generic/$(inc) \
-         $(dir)/$(inc) \
-          ))) $(subst ../, ,$(wildcard ../$(inc) ../os/$(OS_CLASS)/$(inc))) $(inc))  )) 
-
-#INSTALL_INC += $(subst generic/,,$(foreach inc,$(INC), \
-#    $(firstword $(foreach dir,$(SRC_DIRS) .., \
-#    $(addprefix $(INSTALL_INCLUDE)/, \
-#    $(subst $(dir)/, ,$(firstword $(wildcard \
-#         $(dir)/os/$(OS_CLASS)$(B_T_SUFFIX)/$(inc) \
-#         $(dir)/os/posix$(B_T_SUFFIX)/$(inc) \
-#         $(dir)/os/$(OS_CLASS)/$(inc) \
-#         $(dir)/os/posix/$(inc) \
-#         $(dir)/generic$(B_T_SUFFIX)/$(inc) \
-#         $(dir)/generic/$(inc) \
-#         $(dir)/$(inc) \
-#         ../$(inc) ) $(inc) ))) ))))
+         $(dir)/$(inc)))) \
+    $(subst ../, ,$(wildcard ../$(inc) ../os/$(OS_CLASS)/$(inc))) \
+    $(inc)))) 
 
 MAN_DIRECTORY_TARGETS = $(foreach n, $(MANLIST),$(INSTALL_MAN)/man$(n))
 #---------------------------------------------------------------
@@ -850,14 +830,6 @@ $(INSTALL_INCLUDE)/%: ../%
 	@echo "Installing include file $@"
 	@$(INSTALL) -d -m 644 $< $(@D)
 
-#$(INSTALL_INCLUDE)/os/%: %
-#	@echo "Installing os include file $@"
-#	@$(INSTALL) -d -m 644 $< $(@D)
-#
-#$(INSTALL_INCLUDE)/os/%: ../%
-#	@echo "Installing os include file $@"
-#	@$(INSTALL) -d -m 644 $< $(@D)
-
 $(INSTALL_DOC)/%: %
 	@echo "Installing doc $@"
 	@$(INSTALL) -d -m 644 $< $(INSTALL_DOC)