diff --git a/definitions/mars/grib.elda.mpp.def b/definitions/mars/grib.elda.mpp.def
new file mode 100644
index 000000000..ae2eef11e
--- /dev/null
+++ b/definitions/mars/grib.elda.mpp.def
@@ -0,0 +1,5 @@
+alias mars.anoffset=offsetToEndOf4DvarWindow;
+alias mars.number=perturbationNumber;
+
+unalias mars.levtype;
+unalias mars.levelist;
diff --git a/definitions/mars/grib.enda.mpp.def b/definitions/mars/grib.enda.mpp.def
new file mode 100644
index 000000000..53a837ed2
--- /dev/null
+++ b/definitions/mars/grib.enda.mpp.def
@@ -0,0 +1,4 @@
+alias mars.number=perturbationNumber;
+
+unalias mars.levtype;
+unalias mars.levelist;
diff --git a/definitions/mars/type.table b/definitions/mars/type.table
index 1985ee678..edbfb16c3 100644
--- a/definitions/mars/type.table
+++ b/definitions/mars/type.table
@@ -74,3 +74,4 @@
 93 ppm Point value metrics
 94 gwt Weather types
 95 est Ensemble statistics
+96 mpp Model physics perturbations