diff --git a/nnpdf_data/nnpdf_data/commondata/HERA_CC_318GEV/metadata.yaml b/nnpdf_data/nnpdf_data/commondata/HERA_CC_318GEV/metadata.yaml
index 6b9c9a9d00..04cfb83b85 100644
--- a/nnpdf_data/nnpdf_data/commondata/HERA_CC_318GEV/metadata.yaml
+++ b/nnpdf_data/nnpdf_data/commondata/HERA_CC_318GEV/metadata.yaml
@@ -63,8 +63,11 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_CC_318GEV_EM_SIGMARED
-  data_uncertainties: 
-    - uncertainties_EM-SIGMARED.yaml  
+  data_uncertainties: [uncertainties_EM-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_EM-SIGMARED.yaml
   data_central: data_EM-SIGMARED.yaml
   ported_from: HERACOMBCCEM
 - observable_name: EP-SIGMARED
@@ -117,7 +120,10 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_CC_318GEV_EP_SIGMARED
-  data_uncertainties: 
-    - uncertainties_EP-SIGMARED.yaml  
+  data_uncertainties: [uncertainties_EP-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_EP-SIGMARED.yaml
   data_central: data_EP-SIGMARED.yaml
   ported_from: HERACOMBCCEP
diff --git a/nnpdf_data/nnpdf_data/commondata/HERA_NC_225GEV/metadata.yaml b/nnpdf_data/nnpdf_data/commondata/HERA_NC_225GEV/metadata.yaml
index 032d5c0512..5a466c3d93 100644
--- a/nnpdf_data/nnpdf_data/commondata/HERA_NC_225GEV/metadata.yaml
+++ b/nnpdf_data/nnpdf_data/commondata/HERA_NC_225GEV/metadata.yaml
@@ -18,7 +18,7 @@ implemented_observables:
     description: Deep Inelastic Scattering
     label: HERA I+II inclusive NC $e^+p$ 460 GeV
     units: ''
-  process_type: DIS_NCP
+  process_type: DIS_NC
   tables: []
   npoints: []
   ndata: 209
@@ -276,7 +276,10 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_NC_225GEV_EP_SIGMARED
-  data_uncertainties:
-  - uncertainties_EP-SIGMARED.yaml
+  data_uncertainties: [uncertainties_EP-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_EP-SIGMARED.yaml
   data_central: data_EP-SIGMARED.yaml
   ported_from: HERACOMBNCEP460
diff --git a/nnpdf_data/nnpdf_data/commondata/HERA_NC_251GEV/metadata.yaml b/nnpdf_data/nnpdf_data/commondata/HERA_NC_251GEV/metadata.yaml
index c2cf1a7da4..69a409a667 100644
--- a/nnpdf_data/nnpdf_data/commondata/HERA_NC_251GEV/metadata.yaml
+++ b/nnpdf_data/nnpdf_data/commondata/HERA_NC_251GEV/metadata.yaml
@@ -18,7 +18,7 @@ implemented_observables:
     description: Deep Inelastic Scattering
     label: HERA I+II inclusive NC $e^+p$ 575 GeV
     units: ''
-  process_type: DIS_NCP
+  process_type: DIS_NC
   tables: []
   npoints: []
   ndata: 260
@@ -315,7 +315,7 @@ implemented_observables:
         units: ''
       Q2:
         description: Square of momentum transfer
-        label: "$Q2$"
+        label: "$Q^2$"
         units: '$GeV^2$'
       y:
         description: Inelasticity y
@@ -327,7 +327,10 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_NC_251GEV_EP_SIGMARED
-  data_uncertainties:
-  - uncertainties_EP-SIGMARED.yaml
+  data_uncertainties: [uncertainties_EP-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_EP-SIGMARED.yaml
   data_central: data_EP-SIGMARED.yaml
   ported_from: HERACOMBNCEP575
diff --git a/nnpdf_data/nnpdf_data/commondata/HERA_NC_300GEV/metadata.yaml b/nnpdf_data/nnpdf_data/commondata/HERA_NC_300GEV/metadata.yaml
index c905714ead..59643585f9 100644
--- a/nnpdf_data/nnpdf_data/commondata/HERA_NC_300GEV/metadata.yaml
+++ b/nnpdf_data/nnpdf_data/commondata/HERA_NC_300GEV/metadata.yaml
@@ -18,7 +18,7 @@ implemented_observables:
     description: Deep Inelastic Scattering
     label: HERA I+II inclusive NC $e^+p$ 820 GeV
     units: ''
-  process_type: DIS_NCP
+  process_type: DIS_NC
   tables: []
   npoints: []
   ndata: 112
@@ -179,7 +179,10 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_NC_300GEV_EP_SIGMARED
-  data_uncertainties:
-    - uncertainties_EP-SIGMARED.yaml
+  data_uncertainties: [uncertainties_EP-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_EP-SIGMARED.yaml
   data_central: data_EP-SIGMARED.yaml
   ported_from: HERACOMBNCEP820
diff --git a/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV/metadata.yaml b/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV/metadata.yaml
index 090236425c..be7a9d6606 100644
--- a/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV/metadata.yaml
+++ b/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV/metadata.yaml
@@ -18,7 +18,7 @@ implemented_observables:
     description: Deep Inelastic Scattering
     label: HERA I+II inclusive NC $e^-p$
     units: ''
-  process_type: DIS_NCE
+  process_type: DIS_NC
   tables: []
   npoints: []
   ndata: 159
@@ -226,8 +226,11 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_NC_318GEV_EM_SIGMARED
-  data_uncertainties: 
-  - uncertainties_EM-SIGMARED.yaml
+  data_uncertainties: [uncertainties_EM-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_EM-SIGMARED.yaml
   data_central: data_EM-SIGMARED.yaml
   ported_from: HERACOMBNCEM
 - observable_name: EP-SIGMARED
@@ -235,7 +238,7 @@ implemented_observables:
     description: Deep Inelastic Scattering
     label: HERA I+II inclusive NC $e^+p$ 920 GeV
     units: ''
-  process_type: DIS_NCP
+  process_type: DIS_NC
   tables: []
   npoints: []
   ndata: 485
@@ -275,7 +278,10 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_NC_318GEV_EP_SIGMARED
-  data_uncertainties: 
-  - uncertainties_EP-SIGMARED.yaml
+  data_uncertainties: [uncertainties_EP-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_EP-SIGMARED.yaml
   data_central: data_EP-SIGMARED.yaml
   ported_from: HERACOMBNCEP920
diff --git a/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV_EAVG/metadata.yaml b/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV_EAVG/metadata.yaml
index 4fd9250d00..0a1c7cab71 100644
--- a/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV_EAVG/metadata.yaml
+++ b/nnpdf_data/nnpdf_data/commondata/HERA_NC_318GEV_EAVG/metadata.yaml
@@ -18,7 +18,7 @@ implemented_observables:
     description: Deep Inelastic Scattering
     label: HERA comb. $\sigma_{b\bar b}^{\rm red}$
     units: ''
-  process_type: DIS_NCE_BT
+  process_type: DIS_NC
   tables: []
   npoints: []
   ndata: 27
@@ -62,8 +62,11 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_NC_318GEV_EAVG_SIGMARED_BOTTOM
-  data_uncertainties: 
-  - uncertainties_BOTTOM-SIGMARED.yaml
+  data_uncertainties: [uncertainties_BOTTOM-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_BOTTOM-SIGMARED.yaml
   data_central: data_BOTTOM-SIGMARED.yaml
   ported_from: HERACOMB_SIGMARED_B
 - observable_name: CHARM-SIGMARED
@@ -71,7 +74,7 @@ implemented_observables:
     description: Deep Inelastic Scattering
     label: HERA comb. $\sigma_{c\bar c}^{\rm red}$
     units: ''
-  process_type: DIS_NCP_CH
+  process_type: DIS_NC
   tables: []
   npoints: []
   ndata: 52
@@ -115,7 +118,10 @@ implemented_observables:
     operation: 'null'
     FK_tables:
     - - HERA_NC_318GEV_EAVG_SIGMARED_CHARM
-  data_uncertainties: 
-  - uncertainties_CHARM-SIGMARED.yaml
+  data_uncertainties: [uncertainties_CHARM-SIGMARED.yaml]
+  variants:
+    legacy:
+      data_uncertainties:
+      - uncertainties_CHARM-SIGMARED.yaml
   data_central: data_CHARM-SIGMARED.yaml
   ported_from: HERACOMB_SIGMARED_C