diff --git a/src/ansys/api/acp/v0/enum_types.proto b/src/ansys/api/acp/v0/enum_types.proto
index 03ce1cb..7472520 100644
--- a/src/ansys/api/acp/v0/enum_types.proto
+++ b/src/ansys/api/acp/v0/enum_types.proto
@@ -18,3 +18,17 @@ enum RosetteSelectionMethod {
     ANSYS_CLASSIC = 6;
     DIRECTIONS_FROM_TABULAR_VALUES = 7;
 }
+
+//defines the ply type which is used for instance by the solid model
+//extrusion and the post-processing to distinguish between isotropic, 
+//reinforced, and core materials
+enum PlyType {
+    REGULAR = 0;
+    WOVEN = 1;
+    ORTHOTROPIC_HOMOGENEOUS_CORE = 2;
+    ISOTROPIC_HOMOGENEOUS_CORE = 3;
+    HONEYCOMB_CORE = 4;
+    ISOTROPIC = 5;
+    UNDEFINED = 6;
+    ADHESIVE = 7;
+}
\ No newline at end of file
diff --git a/src/ansys/api/acp/v0/material.proto b/src/ansys/api/acp/v0/material.proto
index ee55deb..7188492 100644
--- a/src/ansys/api/acp/v0/material.proto
+++ b/src/ansys/api/acp/v0/material.proto
@@ -7,8 +7,10 @@ import "ansys/api/acp/v0/enum_types.proto";
 // Default CRUD messages
 
 message Properties {
+    //This is only a minimal set. List is not complete yet
     enum_types.StatusType status = 1;
     bool locked = 2;
+    enum_types.PlyType ply_type = 3;
 }
 
 message ObjectInfo {