diff --git a/etc/caseDicts/postProcessing/fields/add b/etc/caseDicts/postProcessing/fields/add
new file mode 100644
index 0000000000..3eea74aff9
--- /dev/null
+++ b/etc/caseDicts/postProcessing/fields/add
@@ -0,0 +1,21 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Web:      www.OpenFOAM.org
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+Description
+    Add a list of fields.
+
+\*---------------------------------------------------------------------------*/
+
+type            add;
+libs            ("libfieldFunctionObjects.so");
+
+fields          (<field names>);
+
+executeControl  writeTime;
+writeControl    writeTime;
+
+// ************************************************************************* //
diff --git a/etc/caseDicts/postProcessing/fields/subtract b/etc/caseDicts/postProcessing/fields/subtract
new file mode 100644
index 0000000000..6f9126cd7d
--- /dev/null
+++ b/etc/caseDicts/postProcessing/fields/subtract
@@ -0,0 +1,21 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+  =========                 |
+  \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox
+   \\    /   O peration     |
+    \\  /    A nd           | Web:      www.OpenFOAM.org
+     \\/     M anipulation  |
+-------------------------------------------------------------------------------
+Description
+    From the first field subtract the remaining fields in the list.
+
+\*---------------------------------------------------------------------------*/
+
+type            subtract;
+libs            ("libfieldFunctionObjects.so");
+
+fields          (<field names>);
+
+executeControl  writeTime;
+writeControl    writeTime;
+
+// ************************************************************************* //