diff --git a/edm4eic.yaml b/edm4eic.yaml
index 9de1462..81db6b6 100644
--- a/edm4eic.yaml
+++ b/edm4eic.yaml
@@ -510,8 +510,6 @@ datatypes:
     Description: "Used to keep track of the correspondence between MC and reconstructed particles"
     Author: "S. Joosten"
     Members:
-      - uint32_t          simID             // Index of corresponding MCParticle (position in MCParticles array)
-      - uint32_t          recID             // Index of corresponding ReconstructedParticle (position in ReconstructedParticles array)
       - float             weight            // weight of this association
     OneToOneRelations :
       - edm4eic::ReconstructedParticle rec  // reference to the reconstructed particle
@@ -521,8 +519,6 @@ datatypes:
     Description: "Association between a Cluster and a MCParticle"
     Author : "S. Joosten"
     Members:
-      - uint32_t          simID             // Index of corresponding MCParticle (position in MCParticles array)
-      - uint32_t          recID             // Index of corresponding Cluster (position in Clusters array)
       - float             weight            // weight of this association
     OneToOneRelations:
       - edm4eic::Cluster  rec               // reference to the cluster
@@ -532,8 +528,6 @@ datatypes:
     Description: "Association between a Track and a MCParticle"
     Author : "S. Joosten"
     Members:
-      - uint32_t          simID             // Index of corresponding MCParticle (position in MCParticles array)
-      - uint32_t          recID             // Index of corresponding Track (position in Tracks array)
       - float             weight            // weight of this association
     OneToOneRelations:
       - edm4eic::Track    rec               // reference to the track
@@ -543,8 +537,6 @@ datatypes:
     Description: "Association between a Vertex and a MCParticle"
     Author : "S. Joosten"
     Members:
-      - uint32_t          simID             // Index of corresponding MCParticle (position in MCParticles array)
-      - uint32_t          recID             // Index of corresponding Vertex (position in Vertices array)
       - float             weight            // weight of this association
     OneToOneRelations:
       - edm4eic::Vertex     rec             // reference to the vertex