diff --git a/masque/label.py b/masque/label.py
index af4f2e2..fc9460c 100644
--- a/masque/label.py
+++ b/masque/label.py
@@ -18,14 +18,11 @@ class Label(PositionableImpl, LayerableImpl, RepeatableImpl, AnnotatableImpl,
     """
     A text annotation with a position and layer (but no size; it is not drawn)
     """
-    __slots__ = ( '_string', 'identifier')
+    __slots__ = ( '_string', )
 
     _string: str
     """ Label string """
 
-    identifier: Tuple
-    """ Arbitrary identifier tuple, useful for keeping track of history when flattening """
-
     '''
     ---- Properties
     '''
@@ -49,9 +46,7 @@ class Label(PositionableImpl, LayerableImpl, RepeatableImpl, AnnotatableImpl,
             layer: layer_t = 0,
             repetition: Optional[Repetition] = None,
             annotations: Optional[annotations_t] = None,
-            identifier: Tuple = (),
             ) -> None:
-        self.identifier = identifier
         self.string = string
         self.offset = numpy.array(offset, dtype=float, copy=True)
         self.layer = layer
@@ -64,7 +59,6 @@ class Label(PositionableImpl, LayerableImpl, RepeatableImpl, AnnotatableImpl,
             offset=self.offset.copy(),
             layer=self.layer,
             repetition=self.repetition,
-            identifier=self.identifier,
             )
 
     def __deepcopy__(self: L, memo: Optional[Dict] = None) -> L:
diff --git a/masque/shapes/arc.py b/masque/shapes/arc.py
index 389d6e0..6554946 100644
--- a/masque/shapes/arc.py
+++ b/masque/shapes/arc.py
@@ -167,7 +167,6 @@ class Arc(Shape, metaclass=AutoSlots):
             annotations: Optional[annotations_t] = None,
             raw: bool = False,
             ) -> None:
-        self.identifier = ()
         if raw:
             assert(isinstance(radii, numpy.ndarray))
             assert(isinstance(angles, numpy.ndarray))
diff --git a/masque/shapes/circle.py b/masque/shapes/circle.py
index 9919831..a9beb19 100644
--- a/masque/shapes/circle.py
+++ b/masque/shapes/circle.py
@@ -55,7 +55,6 @@ class Circle(Shape, metaclass=AutoSlots):
             annotations: Optional[annotations_t] = None,
             raw: bool = False,
             ) -> None:
-        self.identifier = ()
         if raw:
             assert(isinstance(offset, numpy.ndarray))
             self._radius = radius
diff --git a/masque/shapes/ellipse.py b/masque/shapes/ellipse.py
index c97f675..2a51e8e 100644
--- a/masque/shapes/ellipse.py
+++ b/masque/shapes/ellipse.py
@@ -102,7 +102,6 @@ class Ellipse(Shape, metaclass=AutoSlots):
             annotations: Optional[annotations_t] = None,
             raw: bool = False,
             ) -> None:
-        self.identifier = ()
         if raw:
             assert(isinstance(radii, numpy.ndarray))
             assert(isinstance(offset, numpy.ndarray))
diff --git a/masque/shapes/path.py b/masque/shapes/path.py
index e64e380..2539c5b 100644
--- a/masque/shapes/path.py
+++ b/masque/shapes/path.py
@@ -158,7 +158,6 @@ class Path(Shape, metaclass=AutoSlots):
             ) -> None:
         self._cap_extensions = None     # Since .cap setter might access it
 
-        self.identifier = ()
         if raw:
             assert(isinstance(vertices, numpy.ndarray))
             assert(isinstance(offset, numpy.ndarray))
diff --git a/masque/shapes/polygon.py b/masque/shapes/polygon.py
index e778186..05df53b 100644
--- a/masque/shapes/polygon.py
+++ b/masque/shapes/polygon.py
@@ -84,7 +84,6 @@ class Polygon(Shape, metaclass=AutoSlots):
             annotations: Optional[annotations_t] = None,
             raw: bool = False,
             ) -> None:
-        self.identifier = ()
         if raw:
             assert(isinstance(vertices, numpy.ndarray))
             assert(isinstance(offset, numpy.ndarray))
diff --git a/masque/shapes/shape.py b/masque/shapes/shape.py
index d84246f..a36281e 100644
--- a/masque/shapes/shape.py
+++ b/masque/shapes/shape.py
@@ -34,9 +34,6 @@ class Shape(PositionableImpl, LayerableImpl, DoseableImpl, Rotatable, Mirrorable
     """
     __slots__ = ()      # Children should use AutoSlots
 
-    identifier: Tuple
-    """ An arbitrary identifier for the shape, usually empty but used by `Pattern.flatten()` """
-
     def __copy__(self) -> 'Shape':
         cls = self.__class__
         new = cls.__new__(cls)
diff --git a/masque/shapes/text.py b/masque/shapes/text.py
index 229e213..b820bc8 100644
--- a/masque/shapes/text.py
+++ b/masque/shapes/text.py
@@ -75,7 +75,6 @@ class Text(RotatableImpl, Shape, metaclass=AutoSlots):
             annotations: Optional[annotations_t] = None,
             raw: bool = False,
             ) -> None:
-        self.identifier = ()
         if raw:
             assert(isinstance(offset, numpy.ndarray))
             assert(isinstance(mirrored, numpy.ndarray))
diff --git a/masque/subpattern.py b/masque/subpattern.py
index 87e76a3..6c18396 100644
--- a/masque/subpattern.py
+++ b/masque/subpattern.py
@@ -34,7 +34,7 @@ class SubPattern(PositionableImpl, DoseableImpl, RotatableImpl, ScalableImpl, Mi
     SubPattern provides basic support for nesting Pattern objects within each other, by adding
      offset, rotation, scaling, and associated methods.
     """
-    __slots__ = ('_target', '_mirrored', 'identifier')
+    __slots__ = ('_target', '_mirrored')
 
     _target: Optional[str]
     """ The name of the `Pattern` being instanced """
@@ -42,9 +42,6 @@ class SubPattern(PositionableImpl, DoseableImpl, RotatableImpl, ScalableImpl, Mi
     _mirrored: NDArray[numpy.bool_]
     """ Whether to mirror the instance across the x and/or y axes. """
 
-    identifier: Tuple[Any, ...]
-    """ Arbitrary identifier, used internally by some `masque` functions. """
-
     def __init__(
             self,
             target: Optional[str],
@@ -56,7 +53,6 @@ class SubPattern(PositionableImpl, DoseableImpl, RotatableImpl, ScalableImpl, Mi
             scale: float = 1.0,
             repetition: Optional[Repetition] = None,
             annotations: Optional[annotations_t] = None,
-            identifier: Tuple[Any, ...] = (),
             ) -> None:
         """
         Args:
@@ -67,9 +63,7 @@ class SubPattern(PositionableImpl, DoseableImpl, RotatableImpl, ScalableImpl, Mi
             dose: Scaling factor applied to the dose.
             scale: Scaling factor applied to the pattern's geometry.
             repetition: `Repetition` object, default `None`
-            identifier: Arbitrary tuple, used internally by some `masque` functions.
         """
-        self.identifier = identifier
         self.target = target
         self.offset = offset
         self.rotation = rotation