diff --git a/.gitignore b/.gitignore
index 2f66d21..cfcc923 100644
--- a/.gitignore
+++ b/.gitignore
@@ -10,7 +10,7 @@ Gemfile.lock
 InstalledFiles
 _yardoc
 coverage
-doc/
+doc/.~lock.*
 lib/bundler/man
 pkg
 rdoc
diff --git a/docs/The_fOOrth_User_Guide.odt b/docs/The_fOOrth_User_Guide.odt
index d2be0f7..d645edb 100644
Binary files a/docs/The_fOOrth_User_Guide.odt and b/docs/The_fOOrth_User_Guide.odt differ
diff --git a/lib/fOOrth/compiler/context.rb b/lib/fOOrth/compiler/context.rb
index dc431c0..f3de8fe 100644
--- a/lib/fOOrth/compiler/context.rb
+++ b/lib/fOOrth/compiler/context.rb
@@ -52,7 +52,7 @@ module XfOOrth
       current = self[symbol]
 
       unless expect.include?(current)
-        error "Invalid value for #{symbol}: #{current.inspect} not #{expect}"
+        error "F10: Invalid value for #{symbol}: #{current.inspect} not #{expect}"
       end
 
       true
@@ -87,7 +87,7 @@ module XfOOrth
       if (sym = SymbolMap.map(name))
         @data.delete(sym)
       else
-        error "Unable to remove local method #{name}"
+        error "F90: Unable to remove local method #{name}"
       end
     end
 
diff --git a/lib/fOOrth/compiler/context_map_name.rb b/lib/fOOrth/compiler/context_map_name.rb
index a21d309..e6132b2 100644
--- a/lib/fOOrth/compiler/context_map_name.rb
+++ b/lib/fOOrth/compiler/context_map_name.rb
@@ -85,7 +85,7 @@ module XfOOrth
 
     #Error: Unable to find a specification.
     def spec_error
-      error "Unable to find a spec for #{@name} (#{@symbol.inspect})"
+      error "F11: Unable to find a spec for #{@name} (#{@symbol.inspect})"
     end
 
   end