diff --git a/src/create_products.rs b/src/create_products.rs
index 9dc30ec..a382e20 100644
--- a/src/create_products.rs
+++ b/src/create_products.rs
@@ -18,6 +18,7 @@ enum Component {
     Field(String),
 }
 
+#[derive(PartialEq, Eq, PartialOrd, Ord, Hash)]
 enum BuildFrom {
     Service,
     Transfer,
@@ -28,12 +29,35 @@ enum BuildFrom {
     LinkedDataset,
 }
 
+impl From<&String> for BuildFrom {
+    fn from(string: &String) -> Self {
+        match string.as_str() {
+            "S" => BuildFrom::Service,
+            "E" => BuildFrom::Encounter,
+            "CP" => BuildFrom::CodingProcedure,
+            "CD" => BuildFrom::CodingDiagnosis,
+            "T" => BuildFrom::Transfer,
+            "BS" => BuildFrom::LinkedDataset,
+        }
+    }
+}
+
 enum Frequency {
     OnePerSource,
     DailyOrChangeInWard,
     Daily,
 }
 
+impl From<&String> for Frequency {
+    fn from(frequency: &String) -> Self {
+        match frequency.as_str() {
+            "S" => Frequency::OnePerSource,
+            "DOCW" => Frequency::DailyOrChangeInWard,
+            "D" => Frequency::Daily,
+        }
+    }
+}
+
 enum Quantity {
     Constant(f64),
     Extra(String),
@@ -99,7 +123,7 @@ where
     // TODO: Looks kind of bad, any other way around it? I'd rather not have to depend on crossbeam as well
     O: Write + Send + 'static,
 {
-    let mapped_definitions: HashMap<BuildFrom, Definition> = HashMap::new();
+    let mut all_definitions: HashMap<String, Definition> = HashMap::new();
     // Partition the rules by the build from type, so that we'll run all the rules at once for a particular file, which should be much faster
     // then opening files and scanning one at a time. Could also do batches in files
 
@@ -108,8 +132,36 @@ where
     for record in definitions.deserialize::<HashMap<String, String>>() {
         let record = record?;
         // Get the type, then switch based on that, as that's how we determine whether we've got a definition/filter/component/constraint (definition should always come first)
+        let recordType = record.get("Type").unwrap();
+        match recordType.as_str() {
+            "Definition" => {
+                let build_quantity = 
+                all_definitions.insert(
+                    record.get("Name").unwrap().to_owned(),
+                    Definition {
+                        name: record.get("Name").unwrap().to_owned(),
+                        components: vec![],
+                        filters: vec![],
+                        constraints: vec![],
+                        build_from: BuildFrom::from(record.get("BuildFrom").unwrap()),
+                        frequency: Frequency::from(record.get("Frequency").unwrap()),
+                        quantity: ,
+                        duration_fallback: (),
+                    },
+                );
+            }
+            "Filter" => {}
+            "Component" => {}
+            "Constraint" => {}
+            _ => continue,
+        }
     }
 
+    let mut mapped_definitions = all_definitions
+        .into_values()
+        .map(|value| (value.build_from, value))
+        .collect();
+
     // Then read through each file type line by line if there are definitions for that type, and process all records (read into memory the batch size)
     // Probably output to a separate thread (or maybe some kind of limited queue?) to write to disk. Try on same thread to start, then if it's too slow
     // or I want to experiment, split to a separate thread. Probably want to use sync_sender to limit number of messages to a max size in case