FindXKB.cmake explained please

[lI]

##########  FindXKB.cmake in kkde-4.4.4   
//$KDE_PREFIX/share/apps/cmake/modules/FindXKB.cmake



  find_path(X11_XKB_INCLUDE_PATH X11/XKBlib.h "${X11_INC_SEARCH_PATH}")
  if (X11_XKB_INCLUDE_PATH)
    MACRO_PUSH_REQUIRED_VARS()
    set(CMAKE_REQUIRED_LIBRARIES "${X11_LIBRARIES} 
${CMAKE_REQUIRED_LIBRARIES}")
    check_library_exists(X11 XkbLockModifiers "" HAVE_XKB)
    MACRO_POP_REQUIRED_VARS()
    if (HAVE_XKB)
        set(XKB_FOUND TRUE)
    endif (HAVE_XKB)
  endif (X11_XKB_INCLUDE_PATH)

################
I looked in $KDE_PREFIX/share/apps/cmake/modules and I am unable to find 

--MACRO_POP_REQUIRED_VARS
--check_library_exists
could someone explain where these are please?
==================================
And could someone also explain what these functions do (i.e. return)?
--MACRO_PUSH_REQUIRED_VARS()
--MACRO_POP_REQUIRED_VARS()
--check_library_exists(X11 XkbLockModifiers "" HAVE_XKB)