diff --git a/applications/test/dictionary2/Make/options b/applications/test/dictionary2/Make/options
index 41306609f2..8cda22efd1 100644
--- a/applications/test/dictionary2/Make/options
+++ b/applications/test/dictionary2/Make/options
@@ -1 +1 @@
-EXE_INC =
+EXE_INC = -DCOMPAT_OPENFOAM_ORG
diff --git a/applications/test/dictionary2/Test-dictionary2.C b/applications/test/dictionary2/Test-dictionary2.C
index 2f3a58da37..a3eaa6de41 100644
--- a/applications/test/dictionary2/Test-dictionary2.C
+++ b/applications/test/dictionary2/Test-dictionary2.C
@@ -410,6 +410,30 @@ int main(int argc, char *argv[])
             // try_getScalar(dict2.findEntry("bad"), "bad");
             try_getScalar(dict2.findEntry("empty"), "empty");
         }
+
+        #ifdef COMPAT_OPENFOAM_ORG
+        {
+            Info<< nl
+                << "Test openfoam.org compatibility" << nl;
+
+            dictionary mydict
+            (
+                IStringStream
+                (
+                    "scalar 3.14159;\n"
+                    "label 10;\n"
+                )()
+            );
+
+            Info<<"get<scalar> : " << mydict.get<scalar>("scalar") << nl;
+            Info<<"get<label> : " << mydict.get<label>("label") << nl;
+
+            Info<<"lookup<scalar> : " << mydict.lookup<scalar>("scalar") << nl;
+            Info<<"lookup<label> : " << mydict.lookup<label>("label") << nl;
+        }
+        #else
+        Info<< "No openfoam.org compatibility methods" << nl;
+        #endif
     }
 
 
diff --git a/applications/test/primitives/Make/options b/applications/test/primitives/Make/options
index 7ce182425d..770b1ac627 100644
--- a/applications/test/primitives/Make/options
+++ b/applications/test/primitives/Make/options
@@ -1,4 +1,5 @@
 EXE_INC = \
+    -DCOMPAT_OPENFOAM_ORG \
     -I$(LIB_SRC)/fileFormats/lnInclude
 
 EXE_LIBS = \
diff --git a/applications/test/primitives/Test-primitives.C b/applications/test/primitives/Test-primitives.C
index 13a1d8f128..0064400290 100644
--- a/applications/test/primitives/Test-primitives.C
+++ b/applications/test/primitives/Test-primitives.C
@@ -69,7 +69,7 @@ inline Switch readSwitch(const std::string& str)
 
 void printInfo(const Switch& sw)
 {
-    Info<<"Switch " << sw.c_str() << " (enum=" << label(sw.type()) << ")\n";
+    Info<< "Switch " << sw.c_str() << " (enum=" << label(sw.type()) << ")\n";
 }
 
 
@@ -86,6 +86,13 @@ Ostream& toString(Ostream& os, const UList<char>& list)
 }
 
 
+template<class T1, class T2>
+void printValPair(const char* desc, const T1& val1, const T2& val2)
+{
+    Info<< desc << ' ' << val1 << ' ' << val2 << nl;
+}
+
+
 // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
 
 template<class T>
@@ -360,6 +367,21 @@ int main(int argc, char *argv[])
             << "Read " << flatOutput(dstList) << nl;
     }
 
+    #ifdef COMPAT_OPENFOAM_ORG
+    Info<< nl << "compatibility sizes" << nl
+        << "name  com  org" << nl
+        << "----  ---  ---" << nl;
+
+    printValPair("SMALL", SMALL, small);
+    printValPair("GREAT", GREAT, great);
+    printValPair("VSMALL", VSMALL, vSmall);
+    printValPair("VGREAT", VGREAT, vGreat);
+    printValPair("ROOTSMALL", ROOTSMALL, rootSmall);
+    printValPair("ROOTGREAT", ROOTGREAT, rootGreat);
+    #else
+    Info<< nl << "no compatibility sizes" << nl;
+    #endif
+
     if (nFail)
     {
         Info<< nl << "failed " << nFail << " tests" << nl;
diff --git a/src/OpenFOAM/db/dictionary/dictionary.H b/src/OpenFOAM/db/dictionary/dictionary.H
index 8c79e5a699..02325b4638 100644
--- a/src/OpenFOAM/db/dictionary/dictionary.H
+++ b/src/OpenFOAM/db/dictionary/dictionary.H
@@ -1297,20 +1297,6 @@ public:
             return lookup(keyword);
         }
 
-        //- Deprecated(2018-10) find and return a T.
-        //  \deprecated(2018-10) - use get() method
-        template<class T>
-        FOAM_DEPRECATED_FOR(2018-10, "get() method")
-        T lookupType
-        (
-            const word& keyword,
-            bool recursive = false,
-            bool patternMatch = true
-        ) const
-        {
-            return get<T>(keyword, matchOpt(recursive, patternMatch));
-        }
-
         //- Deprecated(2018-10)
         //  \deprecated(2018-10) - use keyType::option version
         FOAM_DEPRECATED_FOR(2018-10, "found(keyType::option)")
@@ -1461,6 +1447,39 @@ public:
         }
 
 
+    // More compatibility
+
+        //- Deprecated(2018-10) find and return a T.
+        //  \deprecated(2018-10) - use get() method
+        template<class T>
+        FOAM_DEPRECATED_FOR(2018-10, "get() method")
+        T lookupType
+        (
+            const word& keyword,
+            bool recursive = false,
+            bool patternMatch = true
+        ) const
+        {
+            return get<T>(keyword, matchOpt(recursive, patternMatch));
+        }
+
+        #ifdef COMPAT_OPENFOAM_ORG
+        //! \cond compat_openfoam_org
+        //  Accommodate name changes from 2019-11
+        template<class T>
+        FOAM_DEPRECATED_FOR(2019-11, "get(). openfoam.org compatibility")
+        T lookup
+        (
+            const word& keyword,
+            bool recursive = false,
+            bool patternMatch = true
+        ) const
+        {
+            return get<T>(keyword, matchOpt(recursive, patternMatch));
+        }
+        #endif
+
+
     // Shortcuts - when a templated classes also inherits from a dictionary
 
         #undef defineDictionaryGetter
diff --git a/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H b/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H
index b3fcf119fe..c75623c51c 100644
--- a/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H
+++ b/src/OpenFOAM/primitives/Scalar/doubleScalar/doubleScalar.H
@@ -55,6 +55,7 @@ namespace Foam
 // Largest and smallest scalar values allowed in certain parts of the code.
 // See std::numeric_limits max(), min(), epsilon()
 constexpr doubleScalar doubleScalarGREAT = 1.0e+15;
+constexpr doubleScalar doubleScalarROOTGREAT = 3.0e+8;
 constexpr doubleScalar doubleScalarVGREAT = 1.0e+300;
 constexpr doubleScalar doubleScalarROOTVGREAT = 1.0e+150;
 constexpr doubleScalar doubleScalarSMALL = 1.0e-15;
diff --git a/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H b/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H
index d9dc53db51..a8546c87a8 100644
--- a/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H
+++ b/src/OpenFOAM/primitives/Scalar/floatScalar/floatScalar.H
@@ -55,6 +55,7 @@ namespace Foam
 // Largest and smallest scalar values allowed in certain parts of the code.
 // See std::numeric_limits max(), min(), epsilon()
 constexpr floatScalar floatScalarGREAT = 1.0e+6;
+constexpr floatScalar floatScalarROOTGREAT = 1.0e+3;
 constexpr floatScalar floatScalarVGREAT = 1.0e+37;
 constexpr floatScalar floatScalarROOTVGREAT = 1.0e+18;
 constexpr floatScalar floatScalarSMALL = 1.0e-6;
diff --git a/src/OpenFOAM/primitives/Scalar/scalar/scalar.H b/src/OpenFOAM/primitives/Scalar/scalar/scalar.H
index 74286eb840..c947c05df2 100644
--- a/src/OpenFOAM/primitives/Scalar/scalar/scalar.H
+++ b/src/OpenFOAM/primitives/Scalar/scalar/scalar.H
@@ -53,6 +53,7 @@ SourceFiles
 namespace Foam
 {
     constexpr scalar GREAT = floatScalarGREAT;
+    constexpr scalar ROOTGREAT = floatScalarROOTGREAT;
     constexpr scalar VGREAT = floatScalarVGREAT;
     constexpr scalar ROOTVGREAT = floatScalarROOTVGREAT;
     constexpr scalar SMALL = floatScalarSMALL;
@@ -60,21 +61,40 @@ namespace Foam
     constexpr scalar VSMALL = floatScalarVSMALL;
     constexpr scalar ROOTVSMALL = floatScalarROOTVSMALL;
 
+    #ifdef COMPAT_OPENFOAM_ORG
+    //! \cond compat_openfoam_org
+    //  Accommodate name changes from 2018-01
+    constexpr scalar great = floatScalarGREAT;
+    constexpr scalar rootGreat = floatScalarROOTGREAT;
+    constexpr scalar vGreat = floatScalarVGREAT;
+    constexpr scalar rootVGreat = floatScalarROOTVGREAT;
+    constexpr scalar small = floatScalarSMALL;
+    constexpr scalar rootSmall = floatScalarROOTSMALL;
+    constexpr scalar vSmall = floatScalarVSMALL;
+    constexpr scalar rootVSmall = floatScalarROOTVSMALL;
+    //! \endcond
+    #endif
+
+
+    //- Read scalar from c-string and return value
     inline scalar readScalar(const char* buf)
     {
         return readFloat(buf);
     }
 
+    //- Read scalar from c-string into argument. Return true on success.
     inline bool readScalar(const char* buf, scalar& val)
     {
         return readFloat(buf, val);
     }
 
+    //- Read scalar from string and return value
     inline scalar readScalar(const std::string& str)
     {
         return readFloat(str);
     }
 
+    //- Read scalar from string into argument. Return true on success.
     inline bool readScalar(const std::string& str, scalar& val)
     {
         return readFloat(str, val);
@@ -101,6 +121,7 @@ namespace Foam
 namespace Foam
 {
     constexpr scalar GREAT = doubleScalarGREAT;
+    constexpr scalar ROOTGREAT = doubleScalarROOTGREAT;
     constexpr scalar VGREAT = doubleScalarVGREAT;
     constexpr scalar ROOTVGREAT = doubleScalarROOTVGREAT;
     constexpr scalar SMALL = doubleScalarSMALL;
@@ -108,21 +129,40 @@ namespace Foam
     constexpr scalar VSMALL = doubleScalarVSMALL;
     constexpr scalar ROOTVSMALL = doubleScalarROOTVSMALL;
 
+    #ifdef COMPAT_OPENFOAM_ORG
+    //! \cond compat_openfoam_org
+    //  Accommodate name changes from 2018-01
+    constexpr scalar great = doubleScalarGREAT;
+    constexpr scalar rootGreat = doubleScalarROOTGREAT;
+    constexpr scalar vGreat = doubleScalarVGREAT;
+    constexpr scalar rootVGreat = doubleScalarROOTVGREAT;
+    constexpr scalar small = doubleScalarSMALL;
+    constexpr scalar rootSmall = doubleScalarROOTSMALL;
+    constexpr scalar vSmall = doubleScalarVSMALL;
+    constexpr scalar rootVSmall = doubleScalarROOTVSMALL;
+    //! \endcond
+    #endif
+
+
+    //- Read scalar from c-string and return value
     inline scalar readScalar(const char* buf)
     {
         return readDouble(buf);
     }
 
+    //- Read scalar from c-string into argument. Return true on success.
     inline bool readScalar(const char* buf, scalar& val)
     {
         return readDouble(buf, val);
     }
 
+    //- Read scalar from string and return value
     inline scalar readScalar(const std::string& str)
     {
         return readDouble(str);
     }
 
+    //- Read scalar from string into argument. Return true on success.
     inline bool readScalar(const std::string& str, scalar& val)
     {
         return readDouble(str, val);