diff --git a/PARAM_DEF/mms1234_sep_mms1_gse.xml b/PARAM_DEF/mms1234_sep_mms1_gse.xml
index f4bff62..3ae34b7 100644
--- a/PARAM_DEF/mms1234_sep_mms1_gse.xml
+++ b/PARAM_DEF/mms1234_sep_mms1_gse.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms1_gse">
+	<reference_parameter>mms1_xyz_gse</reference_parameter>
 	<get>
 		<amdaParam name="mms1_xyz_gse"/>
 		<amdaParam name="mms1234_xyz_bary_gse"/>
 	</get>
-    <process>RADIUS_EARTH*($mms1_xyz_gse-$mms1234_xyz_bary_gse)</process>
+	<process>RADIUS_EARTH*($mms1_xyz_gse-$mms1234_xyz_bary_gse)</process>
 	<output/>
 </param>
diff --git a/PARAM_DEF/mms1234_sep_mms1_gsm.xml b/PARAM_DEF/mms1234_sep_mms1_gsm.xml
index e79ad92..7335240 100644
--- a/PARAM_DEF/mms1234_sep_mms1_gsm.xml
+++ b/PARAM_DEF/mms1234_sep_mms1_gsm.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms1_gsm">
-	<get>
-		<amdaParam name="mms1_xyz_gsm"/>
-		<amdaParam name="mms1234_xyz_bary_gsm"/>
-	</get>
+    <reference_parameter>mms1_xyz_gsm</reference_parameter>
+    <get>
+	<amdaParam name="mms1_xyz_gsm"/>
+	<amdaParam name="mms1234_xyz_bary_gsm"/>
+    </get>
     <process>RADIUS_EARTH*($mms1_xyz_gsm-$mms1234_xyz_bary_gsm)</process>
-	<output/>
+    <output/>
 </param>
diff --git a/PARAM_DEF/mms1234_sep_mms2_gse.xml b/PARAM_DEF/mms1234_sep_mms2_gse.xml
index 1bf0faa..6539379 100644
--- a/PARAM_DEF/mms1234_sep_mms2_gse.xml
+++ b/PARAM_DEF/mms1234_sep_mms2_gse.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms2_gse">
+	<reference_parameter>mms2_xyz_gse</reference_parameter>
 	<get>
 		<amdaParam name="mms2_xyz_gse"/>
 		<amdaParam name="mms1234_xyz_bary_gse"/>
 	</get>
-    <process>RADIUS_EARTH*($mms2_xyz_gse-$mms1234_xyz_bary_gse)</process>
+	<process>RADIUS_EARTH*($mms2_xyz_gse-$mms1234_xyz_bary_gse)</process>
 	<output/>
 </param>
diff --git a/PARAM_DEF/mms1234_sep_mms2_gsm.xml b/PARAM_DEF/mms1234_sep_mms2_gsm.xml
index ef4820c..0313508 100644
--- a/PARAM_DEF/mms1234_sep_mms2_gsm.xml
+++ b/PARAM_DEF/mms1234_sep_mms2_gsm.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms2_gsm">
+	<reference_parameter>mms2_xyz_gsm</reference_parameter>
 	<get>
 		<amdaParam name="mms2_xyz_gsm"/>
 		<amdaParam name="mms1234_xyz_bary_gsm"/>
 	</get>
-    <process>RADIUS_EARTH*($mms2_xyz_gsm-$mms1234_xyz_bary_gsm)</process>
+	<process>RADIUS_EARTH*($mms2_xyz_gsm-$mms1234_xyz_bary_gsm)</process>
 	<output/>
 </param>
diff --git a/PARAM_DEF/mms1234_sep_mms3_gse.xml b/PARAM_DEF/mms1234_sep_mms3_gse.xml
index f71ea14..b922b37 100644
--- a/PARAM_DEF/mms1234_sep_mms3_gse.xml
+++ b/PARAM_DEF/mms1234_sep_mms3_gse.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms3_gse">
+	<reference_parameter>mms3_xyz_gse</reference_parameter>
 	<get>
 		<amdaParam name="mms3_xyz_gse"/>
 		<amdaParam name="mms1234_xyz_bary_gse"/>
 	</get>
-    <process>RADIUS_EARTH*($mms3_xyz_gse-$mms1234_xyz_bary_gse)</process>
+	<process>RADIUS_EARTH*($mms3_xyz_gse-$mms1234_xyz_bary_gse)</process>
 	<output/>
 </param>
diff --git a/PARAM_DEF/mms1234_sep_mms3_gsm.xml b/PARAM_DEF/mms1234_sep_mms3_gsm.xml
index 33e1b60..71497fa 100644
--- a/PARAM_DEF/mms1234_sep_mms3_gsm.xml
+++ b/PARAM_DEF/mms1234_sep_mms3_gsm.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms3_gsm">
+	<reference_parameter>mms3_xyz_gsm</reference_parameter>
 	<get>
 		<amdaParam name="mms3_xyz_gsm"/>
 		<amdaParam name="mms1234_xyz_bary_gsm"/>
 	</get>
-    <process>RADIUS_EARTH*($mms3_xyz_gsm-$mms1234_xyz_bary_gsm)</process>
+	<process>RADIUS_EARTH*($mms3_xyz_gsm-$mms1234_xyz_bary_gsm)</process>
 	<output/>
 </param>
diff --git a/PARAM_DEF/mms1234_sep_mms4_gse.xml b/PARAM_DEF/mms1234_sep_mms4_gse.xml
index cbf47e5..5649084 100644
--- a/PARAM_DEF/mms1234_sep_mms4_gse.xml
+++ b/PARAM_DEF/mms1234_sep_mms4_gse.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms4_gse">
+	<reference_parameter>mms4_xyz_gse</reference_parameter>
 	<get>
 		<amdaParam name="mms4_xyz_gse"/>
 		<amdaParam name="mms1234_xyz_bary_gse"/>
 	</get>
-    <process>RADIUS_EARTH*($mms4_xyz_gse-$mms1234_xyz_bary_gse)</process>
+	<process>RADIUS_EARTH*($mms4_xyz_gse-$mms1234_xyz_bary_gse)</process>
 	<output/>
 </param>
diff --git a/PARAM_DEF/mms1234_sep_mms4_gsm.xml b/PARAM_DEF/mms1234_sep_mms4_gsm.xml
index 4cf2905..8e4aca8 100644
--- a/PARAM_DEF/mms1234_sep_mms4_gsm.xml
+++ b/PARAM_DEF/mms1234_sep_mms4_gsm.xml
@@ -1,9 +1,10 @@
 <?xml version="1.0"?>
 <param xml:id="mms1234_sep_mms4_gsm">
+	<reference_parameter>mms4_xyz_gsm</reference_parameter>
 	<get>
 		<amdaParam name="mms4_xyz_gsm"/>
 		<amdaParam name="mms1234_xyz_bary_gsm"/>
 	</get>
-    <process>RADIUS_EARTH*($mms4_xyz_gsm-$mms1234_xyz_bary_gsm)</process>
+	<process>RADIUS_EARTH*($mms4_xyz_gsm-$mms1234_xyz_bary_gsm)</process>
 	<output/>
 </param>
--
libgit2 0.21.2