diff --git a/extractor/src/extractor.rs b/extractor/src/extractor.rs
index db328b631d0..b724ce384a2 100644
--- a/extractor/src/extractor.rs
+++ b/extractor/src/extractor.rs
@@ -26,8 +26,8 @@ impl Extractor {
             .expect("Failed to parse file");
         let mut visitor = Visitor {
             source: &source,
-            program: vec![Fact::Comment(format!(
-                "Auto-generated FACT file for {}, generated by the cool kids",
+            trap_output: vec![TrapEntry::Comment(format!(
+                "Auto-generated TRAP file for {}",
                 path.display()
             ))],
             counter: -1,
@@ -40,7 +40,7 @@ impl Extractor {
         traverse(&tree, &mut visitor);
 
         &self.parser.reset();
-        Ok(Program(visitor.program))
+        Ok(Program(visitor.trap_output))
     }
 }
 
@@ -65,13 +65,24 @@ fn build_union_type_lookup<'a>(schema: &'a Vec<Entry>) -> Map<&'a TypeName, &'a
 }
 
 struct Visitor<'a> {
-    source: &'a Vec<u8>,
-    program: Vec<Fact>,
-    counter: i32,
+    /// The file path of the source code (as string)
     path: String,
-    stack: Vec<Vec<(Option<&'static str>, Id, TypeName)>>,
+    /// The source code as a UTF-8 byte array
+    source: &'a Vec<u8>,
+    /// The accumulated trap entries
+    trap_output: Vec<TrapEntry>,
+    /// A counter for generating fresh labels
+    counter: i32,
+    /// A lookup table from type name to dbscheme table entries
     tables: Map<&'a TypeName, &'a Entry>,
+    /// A lookup table for union types mapping a type name to its direct members
     union_types: Map<&'a TypeName, &'a Set<TypeName>>,
+    /// A stack for gathering information from hild nodes. Whenever a node is entered
+    /// an empty list is pushed. All children append their data (field name, label, type) to
+    /// the the list. When the visitor leaves a node the list containing the child data is popped
+    /// from the stack and matched against the dbscheme for the node. If the expectations are met
+    /// the corresponding row definitions are added to the trap_output.
+    stack: Vec<Vec<(Option<&'static str>, Label, TypeName)>>,
 }
 
 impl Visitor<'_> {
@@ -113,11 +124,11 @@ impl Visitor<'_> {
         });
         if let Some(Entry::Table { fields, .. }) = table {
             self.counter += 1;
-            let id = Id(self.counter);
-            let loc = Loc(self.counter);
-            self.program.push(Fact::New(Arg::IdArg(id)));
-            self.program.push(Fact::New(Arg::LocArg(loc)));
-            self.program.push(location_for(&self.path, loc, node));
+            let id = Label::Normal(self.counter);
+            let loc = Label::Location(self.counter);
+            self.trap_output.push(TrapEntry::New(id));
+            self.trap_output.push(TrapEntry::New(loc));
+            self.trap_output.push(location_for(&self.path, loc, node));
             let table_name = node_type_name(node.kind(), node.is_named());
             let args: Option<Vec<Arg>>;
             if fields.is_empty() {
@@ -126,8 +137,8 @@ impl Visitor<'_> {
                 args = self.complex_node(&node, fields, child_nodes, id);
             }
             if let Some(args) = args {
-                self.program
-                    .push(Fact::Definition(table_name, id, args, loc));
+                self.trap_output
+                    .push(TrapEntry::Definition(table_name, id, args, loc));
             }
             if let Some(parent) = self.stack.last_mut() {
                 parent.push((
@@ -152,10 +163,10 @@ impl Visitor<'_> {
         &mut self,
         node: &Node,
         fields: &Vec<Field>,
-        child_nodes: Vec<(Option<&str>, Id, TypeName)>,
-        parent_id: Id,
+        child_nodes: Vec<(Option<&str>, Label, TypeName)>,
+        parent_id: Label,
     ) -> Option<Vec<Arg>> {
-        let mut map: Map<&Option<String>, (&Field, Vec<Id>)> = std::collections::BTreeMap::new();
+        let mut map: Map<&Option<String>, (&Field, Vec<Label>)> = std::collections::BTreeMap::new();
         for field in fields {
             map.insert(&field.name, (field, Vec::new()));
         }
@@ -195,7 +206,7 @@ impl Visitor<'_> {
             match &field.storage {
                 Storage::Column => {
                     if child_ids.len() == 1 {
-                        args.push(Arg::IdArg(*child_ids.first().unwrap()));
+                        args.push(Arg::Label(*child_ids.first().unwrap()));
                     } else {
                         is_valid = false;
                         println!(
@@ -217,7 +228,7 @@ impl Visitor<'_> {
                 }
                 Storage::Table { parent, index } => {
                     for child_id in child_ids {
-                        self.program.push(Fact::ChildOf(
+                        self.trap_output.push(TrapEntry::ChildOf(
                             node_type_name(&parent.kind, parent.named),
                             parent_id,
                             match &field.name {
@@ -255,24 +266,24 @@ impl Visitor<'_> {
 // Emit a slice of a source file as an Arg.
 fn sliced_source_arg(source: &Vec<u8>, n: Node) -> Arg {
     let range = n.byte_range();
-    Arg::StringArg(String::from(
+    Arg::String(String::from(
         std::str::from_utf8(&source[range.start..range.end]).expect("Failed to decode string"),
     ))
 }
 
-// Emit a 'Located' fact for the provided node, appropriately calibrated.
-fn location_for<'a>(fp: &String, ident: Loc, n: Node) -> Fact {
+// Emit a 'Located' TrapEntry for the provided node, appropriately calibrated.
+fn location_for<'a>(fp: &String, label: Label, n: Node) -> TrapEntry {
     let start_line = n.start_position().row;
     let start_col = n.start_position().column;
     let end_line = n.end_position().row;
     let end_col = n.end_position().column;
-    Fact::Located(vec![
-        Arg::LocArg(ident),
-        Arg::StringArg(fp.to_owned()),
-        Arg::IntArg(start_line),
-        Arg::IntArg(start_col),
-        Arg::IntArg(end_line),
-        Arg::IntArg(end_col),
+    TrapEntry::Located(vec![
+        Arg::Label(label),
+        Arg::String(fp.to_owned()),
+        Arg::Int(start_line),
+        Arg::Int(start_col),
+        Arg::Int(end_line),
+        Arg::Int(end_col),
     ])
 }
 
@@ -296,34 +307,35 @@ fn traverse(tree: &Tree, visitor: &mut Visitor) {
         }
     }
 }
-pub struct Program(Vec<Fact>);
+
+pub struct Program(Vec<TrapEntry>);
 
 impl fmt::Display for Program {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         let mut text = String::new();
-        for fact in &self.0 {
-            text.push_str(&format!("{}\n", fact));
+        for trap_entry in &self.0 {
+            text.push_str(&format!("{}\n", trap_entry));
         }
         write!(f, "{}", text)
     }
 }
-#[derive(Debug)]
-enum Fact {
+
+enum TrapEntry {
     // @id = *@
-    New(Arg),
+    New(Label),
     // @node_def(self, arg?, location)@
-    Definition(String, Id, Vec<Arg>, Loc),
+    Definition(String, Label, Vec<Arg>, Label),
     // @node_child(self, index, parent)@
-    ChildOf(String, Id, String, Index, Id),
+    ChildOf(String, Label, String, Index, Label),
     // @location(loc, path, r1, c1, r2, c2)
     Located(Vec<Arg>),
     Comment(String),
 }
-impl fmt::Display for Fact {
+impl fmt::Display for TrapEntry {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Fact::New(id) => write!(f, "{} = *", id),
-            Fact::Definition(n, id, args, loc) => {
+            TrapEntry::New(id) => write!(f, "{} = *", id),
+            TrapEntry::Definition(n, id, args, loc) => {
                 let mut args_str = String::new();
                 for arg in args {
                     args_str.push_str(&format!("{}, ", arg));
@@ -337,7 +349,7 @@ impl fmt::Display for Fact {
                     loc
                 )
             }
-            Fact::ChildOf(pname, id, fname, idx, p) => write!(
+            TrapEntry::ChildOf(pname, id, fname, idx, p) => write!(
                 f,
                 "{}({}, {}, {})",
                 escape_name(&format!("{}_{}", &pname, &fname)),
@@ -345,7 +357,7 @@ impl fmt::Display for Fact {
                 idx,
                 p
             ),
-            Fact::Located(args) => write!(
+            TrapEntry::Located(args) => write!(
                 f,
                 "location({}, {}, {}, {}, {}, {})",
                 args.get(0).unwrap(),
@@ -355,28 +367,28 @@ impl fmt::Display for Fact {
                 args.get(4).unwrap(),
                 args.get(5).unwrap(),
             ),
-            Fact::Comment(line) => write!(f, "// {}", line),
+            TrapEntry::Comment(line) => write!(f, "// {}", line),
         }
     }
 }
-// Identifiers of the form #0, #1...
-#[derive(Debug, Copy, Clone)]
-struct Id(i32);
 
-impl fmt::Display for Id {
+#[derive(Debug, Copy, Clone)]
+enum Label {
+    // Identifiers of the form #0, #1...
+    Normal(i32), // #0, #1, etc.
+    // Location identifiers of the form #0_loc, #1_loc...
+    Location(i32), // #0_loc, #1_loc, etc.
+}
+
+impl fmt::Display for Label {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "#{}", self.0)
+        match self {
+            Label::Normal(x) => write!(f, "#{}", x),
+            Label::Location(x) => write!(f, "#{}_loc", x),
+        }
     }
 }
-// Locative identifiers of the form #0_loc, #1_loc...
-#[derive(Debug, Copy, Clone)]
-struct Loc(i32);
 
-impl fmt::Display for Loc {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "#{}_loc", self.0)
-    }
-}
 // Numeric indices.
 #[derive(Debug, Copy, Clone)]
 struct Index(usize);
@@ -387,22 +399,20 @@ impl fmt::Display for Index {
     }
 }
 
-// Some untyped argument to a fact.
+// Some untyped argument to a TrapEntry.
 #[derive(Debug)]
 enum Arg {
-    IntArg(usize),
-    StringArg(String),
-    IdArg(Id),
-    LocArg(Loc),
+    Label(Label),
+    Int(usize),
+    String(String),
 }
 
 impl fmt::Display for Arg {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
-            Arg::IntArg(x) => write!(f, "{}", x),
-            Arg::StringArg(x) => write!(f, "\"{}\"", x.replace("\"", "\"\"")),
-            Arg::IdArg(x) => write!(f, "{}", x),
-            Arg::LocArg(x) => write!(f, "{}", x),
+            Arg::Label(x) => write!(f, "{}", x),
+            Arg::Int(x) => write!(f, "{}", x),
+            Arg::String(x) => write!(f, "\"{}\"", x.replace("\"", "\"\"")),
         }
     }
 }