diff --git a/LUFA/Build/lufa.atprogram.in b/LUFA/Build/lufa.atprogram.in
index 59fedcd43d..d7acc56ecb 100644
--- a/LUFA/Build/lufa.atprogram.in
+++ b/LUFA/Build/lufa.atprogram.in
@@ -38,22 +38,22 @@ LUFA_BUILD_OPTIONAL_VARS  += ATPROGRAM_PROGRAMMER ATPROGRAM_INTERFACE ATPROGRAM_
 #
 # -----------------------------------------------------------------------------
 
-# Sanity-check values of mandatory user-supplied variables
-MCU                  ?= $(error Makefile MCU value not set)
-TARGET               ?= $(error Makefile TARGET value not set)
-
-ifeq ($(MCU),)
-   $(error Makefile MCU option cannot be blank)
-endif
-ifeq ($(TARGET),)
-   $(error Makefile TARGET option cannot be blank)
-endif
+ERROR_IF_UNSET   = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY   = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
 
 # Default values of optionally user-supplied variables
 ATPROGRAM_PROGRAMMER ?= jtagice3
 ATPROGRAM_INTERFACE  ?= jtag
 ATPROGRAM_PORT       ?= 
 
+# Sanity check user supplied values
+$(foreach MANDATORY_VAR, $(LUFA_BUILD_MANDATORY_VARS), $(call ERROR_IF_UNSET, $(MANDATORY_VAR)))
+$(call ERROR_IF_EMPTY, MCU)
+$(call ERROR_IF_EMPTY, TARGET)
+$(call ERROR_IF_EMPTY, ATPROGRAM_PROGRAMMER)
+$(call ERROR_IF_EMPTY, ATPROGRAM_INTERFACE)
+
 # Output Messages
 MSG_ATPROGRAM_CMD    := ' [ATPRGRM] :'
 
diff --git a/LUFA/Build/lufa.avrdude.in b/LUFA/Build/lufa.avrdude.in
index 1f0812b359..12d118adcc 100644
--- a/LUFA/Build/lufa.avrdude.in
+++ b/LUFA/Build/lufa.avrdude.in
@@ -38,22 +38,22 @@ LUFA_BUILD_OPTIONAL_VARS  += AVRDUDE_PROGRAMMER AVRDUDE_PORT AVRDUDE_FLAGS
 #
 # -----------------------------------------------------------------------------
 
-# Sanity-check values of mandatory user-supplied variables
-MCU                ?= $(error Makefile MCU value not set)
-TARGET             ?= $(error Makefile TARGET value not set)
-
-ifeq ($(MCU),)
-   $(error Makefile MCU option cannot be blank)
-endif
-ifeq ($(TARGET),)
-   $(error Makefile TARGET option cannot be blank)
-endif
+ERROR_IF_UNSET   = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY   = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
 
 # Default values of optionally user-supplied variables
 AVRDUDE_PROGRAMMER ?= jtagicemkii
 AVRDUDE_PORT       ?= usb
 AVRDUDE_FLAGS      ?= 
 
+# Sanity check user supplied values
+$(foreach MANDATORY_VAR, $(LUFA_BUILD_MANDATORY_VARS), $(call ERROR_IF_UNSET, $(MANDATORY_VAR)))
+$(call ERROR_IF_EMPTY, MCU)
+$(call ERROR_IF_EMPTY, TARGET)
+$(call ERROR_IF_EMPTY, AVRDUDE_PROGRAMMER)
+$(call ERROR_IF_EMPTY, AVRDUDE_PORT)
+
 # Output Messages
 MSG_AVRDUDE_CMD    := ' [AVRDUDE] :'
 
diff --git a/LUFA/Build/lufa.build.in b/LUFA/Build/lufa.build.in
index 59b81d939d..b1f9efe9cc 100644
--- a/LUFA/Build/lufa.build.in
+++ b/LUFA/Build/lufa.build.in
@@ -55,26 +55,9 @@ LUFA_BUILD_OPTIONAL_VARS  += BOARD OPTIMIZATION C_STANDARD CPP_STANDARD F_CPU C_
 #
 # -----------------------------------------------------------------------------
 
-# Sanity-check values of mandatory user-supplied variables
-MCU            ?= $(error Makefile MCU value not set)
-TARGET         ?= $(error Makefile TARGET value not set)
-ARCH           ?= $(error Makefile ARCH value not set)
-SRC            ?= $(error Makefile SRC value not set)
-F_USB          ?= $(error Makefile F_USB value not set)
-LUFA_PATH      ?= $(error Makefile LUFA_PATH value not set)
-
-ifeq ($(MCU),)
-   $(error Makefile MCU option cannot be blank)
-endif
-ifeq ($(TARGET),)
-   $(error Makefile TARGET option cannot be blank)
-endif
-ifeq ($(ARCH),)
-   $(error Makefile ARCH option cannot be blank)
-endif
-ifeq ($(F_USB),)
-   $(error Makefile F_USB option cannot be blank)
-endif
+ERROR_IF_UNSET     = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY     = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL   = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
 
 # Default values of optionally user-supplied variables
 BOARD           ?= NONE
@@ -87,6 +70,18 @@ CPP_FLAGS       ?=
 ASM_FLAGS       ?=
 CC_FLAGS        ?=
 
+# Sanity check user supplied values
+$(foreach MANDATORY_VAR, $(LUFA_BUILD_MANDATORY_VARS), $(call ERROR_IF_UNSET, $(MANDATORY_VAR)))
+$(call ERROR_IF_EMPTY, MCU)
+$(call ERROR_IF_EMPTY, TARGET)
+$(call ERROR_IF_EMPTY, ARCH)
+$(call ERROR_IF_EMPTY, F_USB)
+$(call ERROR_IF_EMPTY, LUFA_PATH)
+$(call ERROR_IF_EMPTY, BOARD)
+$(call ERROR_IF_EMPTY, OPTIMIZATION)
+$(call ERROR_IF_EMPTY, C_STANDARD)
+$(call ERROR_IF_EMPTY, CPP_STANDARD)
+
 # Determine the utility prefix to use for the selected architecture
 ifeq ($(ARCH), AVR8)
    CROSS        := avr-
diff --git a/LUFA/Build/lufa.cppcheck.in b/LUFA/Build/lufa.cppcheck.in
index 330ec1d492..03f310d094 100644
--- a/LUFA/Build/lufa.cppcheck.in
+++ b/LUFA/Build/lufa.cppcheck.in
@@ -46,6 +46,10 @@ LUFA_BUILD_OPTIONAL_VARS  += CPPCHECK_PATH CPPCHECK_INCLUDES CPPCHECK_EXCLUDES C
 #
 # -----------------------------------------------------------------------------
 
+ERROR_IF_UNSET   = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY   = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
+
 # Default values of optionally user-supplied variables
 CPPCHECK_PATH                ?= .
 CPPCHECK_INCLUDES            ?=
@@ -57,20 +61,23 @@ CPPCHECK_FAIL_ON_WARNING     ?= Y
 CPPCHECK_QUIET               ?= Y
 CPPCHECK_FLAGS               ?= 
 
+# Sanity check user supplied values
+$(foreach MANDATORY_VAR, $(LUFA_BUILD_MANDATORY_VARS), $(call ERROR_IF_UNSET, $(MANDATORY_VAR)))
+$(call ERROR_IF_EMPTY, CPPCHECK_PATH)
+$(call ERROR_IF_EMPTY, CPPCHECK_MSG_TEMPLATE)
+$(call ERROR_IF_EMPTY, CPPCHECK_ENABLE)
+$(call ERROR_IF_NONBOOL, CPPCHECK_FAIL_ON_WARNING)
+$(call ERROR_IF_NONBOOL, CPPCHECK_QUIET)
+
 # Build a default argument list for cppcheck
 BASE_CPPCHECK_FLAGS := --template="$(CPPCHECK_MSG_TEMPLATE)" $(CPPCHECK_INCLUDES:%=-I%) $(CPPCHECK_EXCLUDES:%=-i%) --inline-suppr --force --std=c99
 
 # Sanity check parameters and construct additional command line arguments to cppcheck
-
 ifeq ($(CPPCHECK_FAIL_ON_WARNING), Y)
    BASE_CPPCHECK_FLAGS += --error-exitcode=1
-else ifneq ($(CPPCHECK_FAIL_ON_WARNING), N)
-	$(error CPPCHECK_FAIL_ON_WARNING must be Y or N)
 endif
 ifeq ($(CPPCHECK_QUIET), Y)
    BASE_CPPCHECK_FLAGS += --quiet
-else ifneq ($(CPPCHECK_QUIET), N)
-   $(error CPPCHECK_QUIET must be Y or N)
 endif
 
 # Output Messages
diff --git a/LUFA/Build/lufa.dfu.in b/LUFA/Build/lufa.dfu.in
index 8122bfde32..9c05bb7c11 100644
--- a/LUFA/Build/lufa.dfu.in
+++ b/LUFA/Build/lufa.dfu.in
@@ -36,16 +36,16 @@ LUFA_BUILD_OPTIONAL_VARS  +=
 #
 # -----------------------------------------------------------------------------
 
-# Sanity-check values of mandatory user-supplied variables
-MCU            ?= $(error Makefile MCU value not set)
-TARGET         ?= $(error Makefile TARGET value not set)
+ERROR_IF_UNSET   = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY   = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
 
-ifeq ($(MCU),)
-   $(error Makefile MCU option cannot be blank)
-endif
-ifeq ($(TARGET),)
-   $(error Makefile TARGET option cannot be blank)
-endif
+# Sanity-check values of mandatory user-supplied variables
+$(foreach MANDATORY_VAR, $(LUFA_BUILD_MANDATORY_VARS), $(call ERROR_IF_UNSET, $(MANDATORY_VAR)))
+$(call ERROR_IF_UNSET, MCU)
+$(call ERROR_IF_UNSET, TARGET)
+$(call ERROR_IF_EMPTY, MCU)
+$(call ERROR_IF_EMPTY, TARGET)
 
 # Output Messages
 MSG_COPY_CMD   := ' [CP]      :'
diff --git a/LUFA/Build/lufa.doxygen.in b/LUFA/Build/lufa.doxygen.in
index 3fb950bc3f..4ec52c8a49 100644
--- a/LUFA/Build/lufa.doxygen.in
+++ b/LUFA/Build/lufa.doxygen.in
@@ -35,25 +35,30 @@ LUFA_BUILD_OPTIONAL_VARS  += DOXYGEN_CONF DOXYGEN_FAIL_ON_WARNING DOXYGEN_OVERRI
 #                                configuration file
 # -----------------------------------------------------------------------------
 
-# Sanity-check values of mandatory user-supplied variables
-LUFA_PATH               ?= $(error Makefile LUFA_PATH value not set)
+ERROR_IF_UNSET   = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY   = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
 
 # Default values of optionally user-supplied variables
 DOXYGEN_CONF            ?= Doxygen.conf
 DOXYGEN_FAIL_ON_WARNING ?= Y
 DOXYGEN_OVERRIDE_PARAMS ?= QUIET=YES HTML_STYLESHEET=$(patsubst %/,%,$(LUFA_PATH))/DoxygenPages/Style/Style.css
 
+# Sanity check user supplied values
+$(foreach MANDATORY_VAR, $(LUFA_BUILD_MANDATORY_VARS), $(call ERROR_IF_UNSET, $(MANDATORY_VAR)))
+$(call ERROR_IF_EMPTY, LUFA_PATH)
+$(call ERROR_IF_EMPTY, LUFA_PATH)
+$(call ERROR_IF_NONBOOL, DOXYGEN_FAIL_ON_WARNING)
+
 # Output Messages
 MSG_DOXYGEN_CMD         := ' [DOXYGEN] :'
 
 # Determine Doxygen invocation command
-BASE_DOXYGEN_CMD = ( cat Doxygen.conf $(DOXYGEN_OVERRIDE_PARAMS:%=; echo "%") ) | doxygen -
+BASE_DOXYGEN_CMD = ( cat $(DOXYGEN_CONF) $(DOXYGEN_OVERRIDE_PARAMS:%=; echo "%") ) | doxygen -
 ifeq ($(DOXYGEN_FAIL_ON_WARNING), Y)
    DOXYGEN_CMD = if ( $(BASE_DOXYGEN_CMD) 2>&1 | grep -v "warning: ignoring unsupported tag" ;); then exit 1; fi;
-else ifeq ($(DOXYGEN_FAIL_ON_WARNING), N)
-   DOXYGEN_CMD = $(BASE_DOXYGEN_CMD)
 else
-	$(error DOXYGEN_FAIL_ON_WARNING must be Y or N.)
+   DOXYGEN_CMD = $(BASE_DOXYGEN_CMD)
 endif
 
 doxygen:
diff --git a/LUFA/Build/lufa.sources.in b/LUFA/Build/lufa.sources.in
index 6d28056cc0..6ca480bce5 100644
--- a/LUFA/Build/lufa.sources.in
+++ b/LUFA/Build/lufa.sources.in
@@ -35,13 +35,14 @@ LUFA_BUILD_OPTIONAL_VARS  +=
 #
 # -----------------------------------------------------------------------------
 
-# Sanity-check values of mandatory user-supplied variables
-ARCH           ?= $(error Makefile ARCH value not set)
-LUFA_PATH      ?= $(error Makefile LUFA_PATH value not set)
+ERROR_IF_UNSET   = $(if $(filter undefined, $(origin $(strip $(1)))), $(error Makefile $(strip $(1)) value not set))
+ERROR_IF_EMPTY   = $(if $(strip $($(strip $(1)))), , $(error Makefile $(strip $(1)) option cannot be blank))
+ERROR_IF_NONBOOL = $(if $(filter Y N, $($(strip $(1)))), , $(error Makefile $(strip $(1)) option must be Y or N))
 
-ifeq ($(ARCH),)
-   $(error Makefile ARCH option cannot be blank)
-endif
+# Sanity check user supplied values
+$(foreach MANDATORY_VAR, $(LUFA_BUILD_MANDATORY_VARS), $(call ERROR_IF_UNSET, $(MANDATORY_VAR)))
+$(call ERROR_IF_EMPTY, LUFA_PATH)
+$(call ERROR_IF_EMPTY, ARCH)
 
 # Allow LUFA_ROOT_PATH to be overridden elsewhere to support legacy LUFA makefiles
 LUFA_ROOT_PATH ?= $(patsubst %/,%,$(LUFA_PATH))
diff --git a/LUFA/DoxygenPages/DeviceSupport.txt b/LUFA/DoxygenPages/DeviceSupport.txt
index 37a9200311..165f115dbb 100644
--- a/LUFA/DoxygenPages/DeviceSupport.txt
+++ b/LUFA/DoxygenPages/DeviceSupport.txt
@@ -129,7 +129,8 @@
  
 /**
  *  \page Page_UC3Support Atmel 32-Bit UC3 AVR (UC3)
- *  Note: <i>The AVR32 UC3 device support is currently <b>experimental</b>, and is included for preview purposes only.</i>
+ *
+ *  \warning The AVR32 UC3 device support is currently <b>experimental</b>, and is included for preview purposes only.
  *
  *  \section Sec_UC3Support_Devices Supported Microcontroller Models
  *
@@ -298,7 +299,8 @@
  
 /**
  *  \page Page_XMEGASupport Atmel USB XMEGA AVR (XMEGA)
- *  Note: <i>The XMEGA device support is currently <b>experimental</b> (incomplete and/or non-functional), and is included for preview purposes only.</i>
+ *
+ *  \warning The XMEGA device support is currently <b>experimental</b> (incomplete and/or non-functional), and is included for preview purposes only.
  *
  *  \section Sec_XMEGASupport_Devices Supported Microcontroller Models
  *
diff --git a/LUFA/DoxygenPages/KnownIssues.txt b/LUFA/DoxygenPages/KnownIssues.txt
index 0b191b7c3e..fdefbe2a91 100644
--- a/LUFA/DoxygenPages/KnownIssues.txt
+++ b/LUFA/DoxygenPages/KnownIssues.txt
@@ -13,6 +13,8 @@
   *  - AVR8 Architecture
   *    - No known issues.
   *  - XMEGA Architecture
+  *    \warning The XMEGA device support is currently <b>experimental</b> (incomplete and/or non-functional), and is included for preview purposes only.
+  *
   *    - No demos, bootloaders or projects have been ported for the XMEGA devices in the current release,
   *      although the architecture is supported in the LUFA core library.
   *    - Endpoints of more than 64 bytes are not currently supported in this release.
@@ -22,6 +24,8 @@
   *    - Early revisions of the ATXMEGA128A1U are incompatible with LUFA, due to their various errata
   *      relating to the USB controller.
   *  - UC3 Architecture
+  *    \warning The UC3 device support is currently <b>experimental</b> (incomplete and/or non-functional), and is included for preview purposes only. \n
+  *
   *    - No demos, bootloaders or projects have been ported for the UC3 devices in the current release,
   *      although the architecture is supported in the LUFA core library.
   *    - DMA transfers to and from the USB controller are not yet implemented for this release.
@@ -29,7 +33,7 @@
   *      altered USB controller design.
   *    - The various \c CreateStream() functions for creating standard \c <stdio.h> compatible virtual file
   *      streams are not available on the UC3 architecture, due to a lack of suitable library support.
-  *  - Architecture Independant
+  *  - Architecture Independent
   *    - The HID parser fails for array type elements that have a MIN and MAX usage applied; each element
   *      in the array will receive a unique incrementing usage from the MIN value, up to MAX.
   *    - The current application makefiles do not work if the output directory is not the same directory