diff --git a/source/cseries/cseries.h b/source/cseries/cseries.h
index 90c5c1d6..40d2e013 100644
--- a/source/cseries/cseries.h
+++ b/source/cseries/cseries.h
@@ -95,8 +95,6 @@ typedef byte boolean;
 
 typedef unsigned long tag;
 
-typedef float real;
-
 /* ---------- prototypes/CSERIES.C */
 
 void cseries_initialize(void);
diff --git a/source/math/real_math.h b/source/math/real_math.h
index 7a8431ce..bf16a970 100644
--- a/source/math/real_math.h
+++ b/source/math/real_math.h
@@ -14,6 +14,23 @@ file has inline function assertions.
 
 /* ---------- structures */
 
+typedef float real;
+
+union real_euler_angles3d
+{
+	real n[3];
+	struct { real yaw, pitch, roll; };
+};
+typedef union real_euler_angles3d real_euler_angles3d;
+
+union real_point3d
+{
+	real n[3];
+	struct { real x, y, z; };
+	struct { real u, v, w; };
+};
+typedef union real_point3d real_point3d;
+
 /* ---------- prototypes/REAL_MATH.C */
 
 void real_math_initialize(void);
diff --git a/source/objects/object_types.h b/source/objects/object_types.h
index 811f7e3c..dd21285e 100644
--- a/source/objects/object_types.h
+++ b/source/objects/object_types.h
@@ -1,7 +1,5 @@
 /*
 OBJECT_TYPES.H
-
-header included in hcex build.
 */
 
 #ifndef __OBJECT_TYPES_H
@@ -10,14 +8,43 @@ header included in hcex build.
 
 /* ---------- constants */
 
-/* ---------- macros */
+enum
+{
+	_object_type_biped= 0,
+	_object_type_vehicle,
+	_object_type_weapon,
+	_object_type_equipment,
+	_object_type_garbage,
+	_object_type_projectile,
+	_object_type_scenery,
+	_object_type_machine,
+	_object_type_control,
+	_object_type_light_fixture,
+	_object_type_placeholder,
+	_object_type_sound_scenery,
+	NUMBER_OF_OBJECT_TYPES,
 
-/* ---------- structures */
+	_object_mask_all=                       UNSIGNED_LONG_MAX,
+	_object_mask_unit=                      (FLAG(_object_type_biped)|FLAG(_object_type_vehicle)),
+	_object_mask_biped=                     FLAG(_object_type_biped),
+	_object_mask_vehicle=                   FLAG(_object_type_vehicle),
+	_object_mask_item=                      (FLAG(_object_type_weapon)|FLAG(_object_type_equipment)|FLAG(_object_type_garbage)),
+	_object_mask_weapon=                    FLAG(_object_type_weapon),
+	_object_mask_equipment=                 FLAG(_object_type_equipment),
+	_object_mask_garbage=                   FLAG(_object_type_garbage),
+	_object_mask_projectile=                FLAG(_object_type_projectile),
+	_object_mask_scenery=                   FLAG(_object_type_scenery),
+	_object_mask_sound_scenery=             FLAG(_object_type_sound_scenery),
+	_object_mask_device=                    (FLAG(_object_type_machine)|FLAG(_object_type_control)|FLAG(_object_type_light_fixture)),
+	_object_mask_machine=                   FLAG(_object_type_machine),
+	_object_mask_control=                   FLAG(_object_type_control),
+	_object_mask_light_fixture=             FLAG(_object_type_light_fixture),
+	_object_mask_placeholder=               FLAG(_object_type_placeholder),
 
-/* ---------- prototypes/EXAMPLE.C */
-
-/* ---------- globals */
-
-/* ---------- public code */
+	_object_mask_sightblocking=				(FLAG(_object_type_vehicle)|FLAG(_object_type_scenery)|FLAG(_object_type_machine)),
+	_object_mask_cannot_interpolate=		(FLAG(_object_type_projectile)|FLAG(_object_type_scenery)|FLAG(_object_type_machine)|FLAG(_object_type_control)|
+											FLAG(_object_type_light_fixture)|FLAG(_object_type_placeholder)|FLAG(_object_type_sound_scenery)),
+	_object_mask_remove_on_bsp_switch=		(FLAG(_object_type_scenery)|FLAG(_object_type_light_fixture))
+};
 
 #endif // __OBJECT_TYPES_H
diff --git a/source/objects/placeholder_definitions.c b/source/objects/placeholder_definitions.c
index c6042210..96a46d5d 100644
--- a/source/objects/placeholder_definitions.c
+++ b/source/objects/placeholder_definitions.c
@@ -1,35 +1,55 @@
 /*
 PLACEHOLDER_DEFINITIONS.C
-
-symbols in this file:
-00134D00 0010:
-	_placeholder_initialize (0000)
-00134D10 0010:
-	_placeholder_initialize_for_new_map (0000)
-00134D20 0010:
-	_placeholder_dispose_from_old_map (0000)
-00134D30 0010:
-	_placeholder_dispose (0000)
-00134D40 0010:
-	_placeholder_place (0000)
-00134D50 0010:
-	_placeholder_new (0000)
-00134D60 0010:
-	_placeholder_delete (0000)
 */
 
 /* ---------- headers */
 
-/* ---------- constants */
-
-/* ---------- macros */
-
-/* ---------- structures */
-
-/* ---------- prototypes */
-
-/* ---------- globals */
+#include "cseries.h"
+#include "placeholder_definitions.h"
+#include "real_math.h"
+#include "scenario_definitions.h"
 
 /* ---------- public code */
 
-/* ---------- private code */
+void placeholder_initialize(
+	void)
+{
+	return;
+}
+
+void placeholder_initialize_for_new_map(
+	void)
+{
+	return;
+}
+
+void placeholder_dispose_from_old_map(
+	void)
+{
+	return;
+}
+
+void placeholder_dispose(
+	void)
+{
+	return;
+}
+
+void placeholder_place(
+	long placeholder_index,
+	struct scenario_placeholder_datum *scenario_placeholder)
+{
+	return;
+}
+
+boolean placeholder_new(
+	long object_index)
+{
+	return TRUE;
+}
+
+void placeholder_delete(
+	long placeholder_index)
+{
+	return;
+}
diff --git a/source/objects/placeholder_definitions.h b/source/objects/placeholder_definitions.h
index 1120fdef..c07b03d5 100644
--- a/source/objects/placeholder_definitions.h
+++ b/source/objects/placeholder_definitions.h
@@ -16,6 +16,14 @@ header included in hcex build.
 
 /* ---------- prototypes/EXAMPLE.C */
 
+void placeholder_initialize(void);
+void placeholder_initialize_for_new_map(void);
+void placeholder_dispose_from_old_map(void);
+void placeholder_dispose(void);
+void placeholder_place(long placeholder_index, struct scenario_placeholder_datum *scenario_placeholder);
+boolean placeholder_new(long object_index);
+void placeholder_delete(long placeholder_index);
+
 /* ---------- globals */
 
 /* ---------- public code */
diff --git a/source/scenario/scenario_definitions.h b/source/scenario/scenario_definitions.h
index a6f516b4..c82662f4 100644
--- a/source/scenario/scenario_definitions.h
+++ b/source/scenario/scenario_definitions.h
@@ -14,6 +14,24 @@ header included in hcex build.
 
 /* ---------- structures */
 
+struct scenario_object_datum
+{
+	short palette_entry_index;
+	short name_index;
+	word placement_flags;
+	short variant_number;
+	real_point3d position;
+	real_euler_angles3d rotation;
+	word on_bsp_flags;
+	word misc_flags;
+	unsigned long unused;
+};
+
+struct scenario_placeholder_datum
+{
+	struct scenario_object_datum object;
+};
+
 /* ---------- prototypes/EXAMPLE.C */
 
 /* ---------- globals */