diff --git a/README.markdown b/README.markdown
index 897d0bd..7b1d9bf 100644
--- a/README.markdown
+++ b/README.markdown
@@ -33,7 +33,8 @@ TODO
 
 For 0.6:
 
-*   declared `inputs` `outputs` `trashes` on the `vector` type.
+*   declared `inputs` `outputs` `trashes` on the `vector` type...
+    *   we need to get these 3 things onto the type, and also onto routine types
 *   `goto` (tail call) a routine or a vector.
 *   A more involved demo for the C64 — one that sets up an interrupt.
 
diff --git a/src/sixtypical/analyzer.py b/src/sixtypical/analyzer.py
index 96c88ba..518a831 100644
--- a/src/sixtypical/analyzer.py
+++ b/src/sixtypical/analyzer.py
@@ -2,7 +2,8 @@
 
 from sixtypical.ast import Program, Routine, Block, Instr
 from sixtypical.model import (
-    TYPE_BYTE, TYPE_BYTE_TABLE, TYPE_ROUTINE, TYPE_VECTOR,
+    TYPE_BYTE, TYPE_BYTE_TABLE,
+    RoutineType, VectorType,
     ConstantRef, LocationRef,
     REG_A, FLAG_Z, FLAG_N, FLAG_V, FLAG_C
 )
@@ -224,7 +225,7 @@ def analyze_instr(instr, context, routines):
     elif opcode == 'copy':
         if src.type == dest.type:
             pass
-        elif src.type == TYPE_ROUTINE and dest.type == TYPE_VECTOR:
+        elif isinstance(src.type, RoutineType) and isinstance(dest.type, VectorType):
             pass
         else:
             raise TypeMismatchError((src, dest))
diff --git a/src/sixtypical/compiler.py b/src/sixtypical/compiler.py
index b648400..9be5a7a 100644
--- a/src/sixtypical/compiler.py
+++ b/src/sixtypical/compiler.py
@@ -3,7 +3,8 @@
 from sixtypical.ast import Program, Routine, Block, Instr
 from sixtypical.model import (
     ConstantRef, LocationRef,
-    TYPE_BIT, TYPE_ROUTINE, TYPE_VECTOR,
+    TYPE_BIT,
+    RoutineType, VectorType,
     REG_A, REG_X, REG_Y, FLAG_Z, FLAG_N, FLAG_V, FLAG_C
 )
 from sixtypical.emitter import Byte, Label, Offset
@@ -242,7 +243,8 @@ class Compiler(object):
             self.compile_block(instr.block)
             self.emitter.emit(CLI())
         elif opcode == 'copy':
-            if src.type in (TYPE_ROUTINE, TYPE_VECTOR) and dest.type == TYPE_VECTOR:
+            if isinstance(src.type, (RoutineType, VectorType)) and \
+               isinstance(dest.type, VectorType):
                 src_label = self.labels[src.name]
                 dest_label = self.labels[dest.name]
                 self.emitter.emit(LDA(Absolute(src_label)))
diff --git a/src/sixtypical/model.py b/src/sixtypical/model.py
index 46fe528..3c356df 100644
--- a/src/sixtypical/model.py
+++ b/src/sixtypical/model.py
@@ -17,8 +17,43 @@ class Type(object):
 TYPE_BIT = Type('bit')
 TYPE_BYTE = Type('byte')
 TYPE_BYTE_TABLE = Type('byte table')
-TYPE_ROUTINE = Type('routine')
-TYPE_VECTOR = Type('vector')      # the mem loc contains an address of a routine
+
+
+class InteractionConstrainedType(Type):
+    """Used for routines and vectors."""
+    def __init__(self, name, inputs=None, outputs=None, trashes=None):
+        self.name = name
+        self.inputs = inputs or []
+        self.outputs = outputs or []
+        self.trashes = trashes or []
+
+    def __repr__(self):
+        return 'RoutineType(%r, inputs=%r, outputs=%r, trashes=%r)' % (
+            self.name, self.inputs, self.outputs, self.trashes
+        )
+
+    def __eq__(self, other):
+        return isinstance(other, RoutineType) and (
+            other.name == self.name and
+            other.inputs == self.inputs and
+            other.outputs == self.outputs and
+            other.trashes == self.trashes
+        )
+
+    def __hash__(self):
+        return hash(self.name) ^ hash(self.inputs) ^ hash(self.outputs) ^ hash(self.trashes)
+
+
+class RoutineType(InteractionConstrainedType):
+    """This memory location contains the code for a routine."""
+    def __init__(self, **kwargs):
+        super(RoutineType, self).__init__('routine', **kwargs)
+
+
+class VectorType(InteractionConstrainedType):
+    """This memory location contains the address of a routine."""
+    def __init__(self, **kwargs):
+        super(VectorType, self).__init__('vector', **kwargs)
 
 
 class Ref(object):
diff --git a/src/sixtypical/parser.py b/src/sixtypical/parser.py
index ea26f4d..42095b6 100644
--- a/src/sixtypical/parser.py
+++ b/src/sixtypical/parser.py
@@ -4,7 +4,8 @@ import re
 
 from sixtypical.ast import Program, Defn, Routine, Block, Instr
 from sixtypical.model import (
-    TYPE_BIT, TYPE_BYTE, TYPE_BYTE_TABLE, TYPE_ROUTINE, TYPE_VECTOR,
+    TYPE_BIT, TYPE_BYTE, TYPE_BYTE_TABLE,
+    RoutineType, VectorType,
     LocationRef, ConstantRef
 )
 
@@ -115,7 +116,13 @@ class Parser(object):
             name = routine.name
             if name in self.symbols:
                 raise SyntaxError(name)
-            self.symbols[name] = SymEntry(routine, LocationRef(TYPE_ROUTINE, name))
+            ref = LocationRef(
+                RoutineType(inputs=routine.inputs,
+                            outputs=routine.outputs,
+                            trashes=routine.trashes
+                ), name
+            )
+            self.symbols[name] = SymEntry(routine, ref)
             routines.append(routine)
         self.scanner.check_type('EOF')
         return Program(defns=defns, routines=routines)
@@ -128,13 +135,15 @@ class Parser(object):
                 type = TYPE_BYTE_TABLE
         else:
             self.scanner.expect('vector')
-            type = TYPE_VECTOR
+            type = 'vector'
         self.scanner.check_type('identifier')
         name = self.scanner.token
         self.scanner.scan()
 
         (inputs, outputs, trashes) = self.constraints()
-        if type != TYPE_VECTOR and (inputs or outputs or trashes):
+        if type == 'vector':
+            type = VectorType(inputs=inputs, outputs=outputs, trashes=trashes)
+        elif inputs or outputs or trashes:
             raise SyntaxError("Cannot apply constraints to non-vector type")
 
         addr = None
@@ -260,7 +269,7 @@ class Parser(object):
             self.scanner.scan()
             if name not in self.symbols:
                 raise SyntaxError('Undefined routine "%s"' % name)
-            if self.symbols[name].model.type != TYPE_ROUTINE:
+            if not isinstance(self.symbols[name].model.type, RoutineType):
                 raise SyntaxError('Illegal call of non-routine "%s"' % name)
             return Instr(opcode=opcode, name=name, dest=None, src=None)
         elif self.scanner.token in ("copy",):