diff --git a/Modules/CheckFunctionExists.cmake b/Modules/CheckFunctionExists.cmake
index a0ebfa2c7..7690ec34e 100644
--- a/Modules/CheckFunctionExists.cmake
+++ b/Modules/CheckFunctionExists.cmake
@@ -4,6 +4,10 @@
 # CHECK_FUNCTION_EXISTS - macro which checks if the function exists
 # FUNCTION - the name of the function
 # VARIABLE - variable to store the result
+# 
+# If CMAKE_REQUIRED_FLAGS is set then those flags will be passed into the
+# compile of the program likewise if CMAKE_REQUIRED_LIBRARIES is set then
+# those libraries will be linked against the test program
 #
 
 MACRO(CHECK_FUNCTION_EXISTS FUNCTION VARIABLE)
diff --git a/Modules/CheckIncludeFile.cmake b/Modules/CheckIncludeFile.cmake
index 0459fb357..ecb6fdcc9 100644
--- a/Modules/CheckIncludeFile.cmake
+++ b/Modules/CheckIncludeFile.cmake
@@ -5,7 +5,9 @@
 # INCLUDE - name of include file
 # VARIABLE - variable to return result
 #
-
+# an optional third argument is the CFlags to add to the compile line 
+# or you can use CMAKE_REQUIRED_FLAGS
+#
 MACRO(CHECK_INCLUDE_FILE INCLUDE VARIABLE)
   IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
     SET(MACRO_CHECK_INCLUDE_FILE_FLAGS ${CMAKE_REQUIRED_FLAGS})
diff --git a/Modules/CheckIncludeFileCXX.cmake b/Modules/CheckIncludeFileCXX.cmake
index a5c91080f..9eb5d7dda 100644
--- a/Modules/CheckIncludeFileCXX.cmake
+++ b/Modules/CheckIncludeFileCXX.cmake
@@ -4,7 +4,8 @@
 # CHECK_INCLUDE_FILE - macro which checks the include file exists.
 # INCLUDE - name of include file
 # VARIABLE - variable to return result
-# OPTIONAL - a third argument can be extra flags which are passed to the compiler
+#
+# a third argument can be passed containing extra flags for the compiler
 #
 
 MACRO(CHECK_INCLUDE_FILE_CXX INCLUDE VARIABLE)
diff --git a/Modules/CheckIncludeFiles.cmake b/Modules/CheckIncludeFiles.cmake
index 589f4ae6b..4c578873a 100644
--- a/Modules/CheckIncludeFiles.cmake
+++ b/Modules/CheckIncludeFiles.cmake
@@ -5,6 +5,9 @@
 # INCLUDE - list of files to include
 # VARIABLE - variable to return result
 #
+# If CMAKE_REQUIRED_FLAGS is set then those flags will be passed into the
+# compile of the program
+
 
 MACRO(CHECK_INCLUDE_FILES INCLUDE VARIABLE)
   IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
diff --git a/Modules/CheckLibraryExists.cmake b/Modules/CheckLibraryExists.cmake
index 830d87986..c19568fd4 100644
--- a/Modules/CheckLibraryExists.cmake
+++ b/Modules/CheckLibraryExists.cmake
@@ -5,6 +5,10 @@
 # FUNCTION - the name of the function
 # VARIABLE - variable to store the result
 #
+# If CMAKE_REQUIRED_FLAGS is set then those flags will be passed into the
+# compile of the program likewise if CMAKE_REQUIRED_LIBRARIES is set then
+# those libraries will be linked against the test program
+
 
 MACRO(CHECK_LIBRARY_EXISTS LIBRARY FUNCTION LOCATION VARIABLE)
   IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
diff --git a/Modules/CheckSymbolExists.cmake b/Modules/CheckSymbolExists.cmake
index 2e75ad84c..cc1ca75f4 100644
--- a/Modules/CheckSymbolExists.cmake
+++ b/Modules/CheckSymbolExists.cmake
@@ -6,6 +6,10 @@
 # FILES  - include files to check
 # VARIABLE - variable to return result
 #
+# If CMAKE_REQUIRED_FLAGS is set then those flags will be passed into the
+# compile of the program likewise if CMAKE_REQUIRED_LIBRARIES is set then
+# those libraries will be linked against the test program
+
 
 MACRO(CHECK_SYMBOL_EXISTS SYMBOL FILES VARIABLE)
   IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
diff --git a/Modules/CheckVariableExists.cmake b/Modules/CheckVariableExists.cmake
index 14fdcd2ca..ed1dfb306 100644
--- a/Modules/CheckVariableExists.cmake
+++ b/Modules/CheckVariableExists.cmake
@@ -4,7 +4,12 @@
 # VAR - the name of the variable
 # VARIABLE - variable to store the result
 #
-
+# If CMAKE_REQUIRED_FLAGS is set then those flags will be passed into the
+# compile of the program likewise if CMAKE_REQUIRED_LIBRARIES is set then
+# those libraries will be linked against the test program
+#
+# only for C variables
+#
 MACRO(CHECK_VARIABLE_EXISTS VAR VARIABLE)
   IF("${VARIABLE}" MATCHES "^${VARIABLE}$")
     SET(MACRO_CHECK_VARIABLE_DEFINITIONS