diff --git a/stix2/observables.py b/stix2/observables.py
index 366e007..fd66406 100644
--- a/stix2/observables.py
+++ b/stix2/observables.py
@@ -5,6 +5,8 @@ embedded in Email Message objects, inherit from _STIXBase instead of Observable
 and do not have a '_type' attribute.
 """
 
+from collections import OrderedDict
+
 from .base import _Extension, _Observable, _STIXBase
 from .exceptions import (AtLeastOnePropertyError, DependentPropertiesError,
                          ParseError)
@@ -75,13 +77,14 @@ class ExtensionsProperty(DictionaryProperty):
 
 class Artifact(_Observable):
     _type = 'artifact'
-    _properties = {
-        'type': TypeProperty(_type),
-        'mime_type': StringProperty(),
-        'payload_bin': BinaryProperty(),
-        'url': StringProperty(),
-        'hashes': HashesProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('mime_type', StringProperty()),
+        ('payload_bin', BinaryProperty()),
+        ('url', StringProperty()),
+        ('hashes', HashesProperty()),
+    ])
 
     def _check_object_constraints(self):
         super(Artifact, self)._check_object_constraints()
@@ -91,54 +94,59 @@ class Artifact(_Observable):
 
 class AutonomousSystem(_Observable):
     _type = 'autonomous-system'
-    _properties = {
-        'type': TypeProperty(_type),
-        'number': IntegerProperty(),
-        'name': StringProperty(),
-        'rir': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('number', IntegerProperty()),
+        ('name', StringProperty()),
+        ('rir', StringProperty()),
+    ])
 
 
 class Directory(_Observable):
     _type = 'directory'
-    _properties = {
-        'type': TypeProperty(_type),
-        'path': StringProperty(required=True),
-        'path_enc': StringProperty(),
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('path', StringProperty(required=True)),
+        ('path_enc', StringProperty()),
         # these are not the created/modified timestamps of the object itself
-        'created': TimestampProperty(),
-        'modified': TimestampProperty(),
-        'accessed': TimestampProperty(),
-        'contains_refs': ListProperty(ObjectReferenceProperty(valid_types=['file', 'directory'])),
-    }
+        ('created', TimestampProperty()),
+        ('modified', TimestampProperty()),
+        ('accessed', TimestampProperty()),
+        ('contains_refs', ListProperty(ObjectReferenceProperty(valid_types=['file', 'directory']))),
+    ])
 
 
 class DomainName(_Observable):
     _type = 'domain-name'
-    _properties = {
-        'type': TypeProperty(_type),
-        'value': StringProperty(required=True),
-        'resolves_to_refs': ListProperty(ObjectReferenceProperty(valid_types=['ipv4-addr', 'ipv6-addr', 'domain-name'])),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('value', StringProperty(required=True)),
+        ('resolves_to_refs', ListProperty(ObjectReferenceProperty(valid_types=['ipv4-addr', 'ipv6-addr', 'domain-name']))),
+    ])
 
 
 class EmailAddress(_Observable):
     _type = 'email-addr'
-    _properties = {
-        'type': TypeProperty(_type),
-        'value': StringProperty(required=True),
-        'display_name': StringProperty(),
-        'belongs_to_ref': ObjectReferenceProperty(valid_types='user-account'),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('value', StringProperty(required=True)),
+        ('display_name', StringProperty()),
+        ('belongs_to_ref', ObjectReferenceProperty(valid_types='user-account')),
+    ])
 
 
 class EmailMIMEComponent(_STIXBase):
-    _properties = {
-        'body': StringProperty(),
-        'body_raw_ref': ObjectReferenceProperty(valid_types=['artifact', 'file']),
-        'content_type': StringProperty(),
-        'content_disposition': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('body', StringProperty()),
+        ('body_raw_ref', ObjectReferenceProperty(valid_types=['artifact', 'file'])),
+        ('content_type', StringProperty()),
+        ('content_disposition', StringProperty()),
+    ])
 
     def _check_object_constraints(self):
         super(EmailMIMEComponent, self)._check_object_constraints()
@@ -147,23 +155,24 @@ class EmailMIMEComponent(_STIXBase):
 
 class EmailMessage(_Observable):
     _type = 'email-message'
-    _properties = {
-        'type': TypeProperty(_type),
-        'is_multipart': BooleanProperty(required=True),
-        'date': TimestampProperty(),
-        'content_type': StringProperty(),
-        'from_ref': ObjectReferenceProperty(valid_types='email-addr'),
-        'sender_ref': ObjectReferenceProperty(valid_types='email-addr'),
-        'to_refs': ListProperty(ObjectReferenceProperty(valid_types='email-addr')),
-        'cc_refs': ListProperty(ObjectReferenceProperty(valid_types='email-addr')),
-        'bcc_refs': ListProperty(ObjectReferenceProperty(valid_types='email-addr')),
-        'subject': StringProperty(),
-        'received_lines': ListProperty(StringProperty),
-        'additional_header_fields': DictionaryProperty(),
-        'body': StringProperty(),
-        'body_multipart': ListProperty(EmbeddedObjectProperty(type=EmailMIMEComponent)),
-        'raw_email_ref': ObjectReferenceProperty(valid_types='artifact'),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('is_multipart', BooleanProperty(required=True)),
+        ('date', TimestampProperty()),
+        ('content_type', StringProperty()),
+        ('from_ref', ObjectReferenceProperty(valid_types='email-addr')),
+        ('sender_ref', ObjectReferenceProperty(valid_types='email-addr')),
+        ('to_refs', ListProperty(ObjectReferenceProperty(valid_types='email-addr'))),
+        ('cc_refs', ListProperty(ObjectReferenceProperty(valid_types='email-addr'))),
+        ('bcc_refs', ListProperty(ObjectReferenceProperty(valid_types='email-addr'))),
+        ('subject', StringProperty()),
+        ('received_lines', ListProperty(StringProperty)),
+        ('additional_header_fields', DictionaryProperty()),
+        ('body', StringProperty()),
+        ('body_multipart', ListProperty(EmbeddedObjectProperty(type=EmailMIMEComponent))),
+        ('raw_email_ref', ObjectReferenceProperty(valid_types='artifact')),
+    ])
 
     def _check_object_constraints(self):
         super(EmailMessage, self)._check_object_constraints()
@@ -174,82 +183,88 @@ class EmailMessage(_Observable):
 
 
 class ArchiveExt(_Extension):
-    _properties = {
-        'contains_refs': ListProperty(ObjectReferenceProperty(valid_types='file'), required=True),
-        'version': StringProperty(),
-        'comment': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('contains_refs', ListProperty(ObjectReferenceProperty(valid_types='file'), required=True)),
+        ('version', StringProperty()),
+        ('comment', StringProperty()),
+    ])
 
 
 class AlternateDataStream(_STIXBase):
-    _properties = {
-        'name': StringProperty(required=True),
-        'hashes': HashesProperty(),
-        'size': IntegerProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('name', StringProperty(required=True)),
+        ('hashes', HashesProperty()),
+        ('size', IntegerProperty()),
+    ])
 
 
 class NTFSExt(_Extension):
-    _properties = {
-        'sid': StringProperty(),
-        'alternate_data_streams': ListProperty(EmbeddedObjectProperty(type=AlternateDataStream)),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('sid', StringProperty()),
+        ('alternate_data_streams', ListProperty(EmbeddedObjectProperty(type=AlternateDataStream))),
+    ])
 
 
 class PDFExt(_Extension):
-    _properties = {
-        'version': StringProperty(),
-        'is_optimized': BooleanProperty(),
-        'document_info_dict': DictionaryProperty(),
-        'pdfid0': StringProperty(),
-        'pdfid1': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('version', StringProperty()),
+        ('is_optimized', BooleanProperty()),
+        ('document_info_dict', DictionaryProperty()),
+        ('pdfid0', StringProperty()),
+        ('pdfid1', StringProperty()),
+    ])
 
 
 class RasterImageExt(_Extension):
-    _properties = {
-        'image_height': IntegerProperty(),
-        'image_weight': IntegerProperty(),
-        'bits_per_pixel': IntegerProperty(),
-        'image_compression_algorithm': StringProperty(),
-        'exif_tags': DictionaryProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('image_height', IntegerProperty()),
+        ('image_weight', IntegerProperty()),
+        ('bits_per_pixel', IntegerProperty()),
+        ('image_compression_algorithm', StringProperty()),
+        ('exif_tags', DictionaryProperty()),
+    ])
 
 
 class WindowsPEOptionalHeaderType(_STIXBase):
-    _properties = {
-        'magic_hex': HexProperty(),
-        'major_linker_version': IntegerProperty(),
-        'minor_linker_version': IntegerProperty(),
-        'size_of_code': IntegerProperty(),
-        'size_of_initialized_data': IntegerProperty(),
-        'size_of_uninitialized_data': IntegerProperty(),
-        'address_of_entry_point': IntegerProperty(),
-        'base_of_code': IntegerProperty(),
-        'base_of_data': IntegerProperty(),
-        'image_base': IntegerProperty(),
-        'section_alignment': IntegerProperty(),
-        'file_alignment': IntegerProperty(),
-        'major_os_version': IntegerProperty(),
-        'minor_os_version': IntegerProperty(),
-        'major_image_version': IntegerProperty(),
-        'minor_image_version': IntegerProperty(),
-        'major_subsystem_version': IntegerProperty(),
-        'minor_subsystem_version': IntegerProperty(),
-        'win32_version_value_hex': HexProperty(),
-        'size_of_image': IntegerProperty(),
-        'size_of_headers': IntegerProperty(),
-        'checksum_hex': HexProperty(),
-        'subsystem_hex': HexProperty(),
-        'dll_characteristics_hex': HexProperty(),
-        'size_of_stack_reserve': IntegerProperty(),
-        'size_of_stack_commit': IntegerProperty(),
-        'size_of_heap_reserve': IntegerProperty(),
-        'size_of_heap_commit': IntegerProperty(),
-        'loader_flags_hex': HexProperty(),
-        'number_of_rva_and_sizes': IntegerProperty(),
-        'hashes': HashesProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('magic_hex', HexProperty()),
+        ('major_linker_version', IntegerProperty()),
+        ('minor_linker_version', IntegerProperty()),
+        ('size_of_code', IntegerProperty()),
+        ('size_of_initialized_data', IntegerProperty()),
+        ('size_of_uninitialized_data', IntegerProperty()),
+        ('address_of_entry_point', IntegerProperty()),
+        ('base_of_code', IntegerProperty()),
+        ('base_of_data', IntegerProperty()),
+        ('image_base', IntegerProperty()),
+        ('section_alignment', IntegerProperty()),
+        ('file_alignment', IntegerProperty()),
+        ('major_os_version', IntegerProperty()),
+        ('minor_os_version', IntegerProperty()),
+        ('major_image_version', IntegerProperty()),
+        ('minor_image_version', IntegerProperty()),
+        ('major_subsystem_version', IntegerProperty()),
+        ('minor_subsystem_version', IntegerProperty()),
+        ('win32_version_value_hex', HexProperty()),
+        ('size_of_image', IntegerProperty()),
+        ('size_of_headers', IntegerProperty()),
+        ('checksum_hex', HexProperty()),
+        ('subsystem_hex', HexProperty()),
+        ('dll_characteristics_hex', HexProperty()),
+        ('size_of_stack_reserve', IntegerProperty()),
+        ('size_of_stack_commit', IntegerProperty()),
+        ('size_of_heap_reserve', IntegerProperty()),
+        ('size_of_heap_commit', IntegerProperty()),
+        ('loader_flags_hex', HexProperty()),
+        ('number_of_rva_and_sizes', IntegerProperty()),
+        ('hashes', HashesProperty()),
+    ])
 
     def _check_object_constraints(self):
         super(WindowsPEOptionalHeaderType, self)._check_object_constraints()
@@ -257,53 +272,56 @@ class WindowsPEOptionalHeaderType(_STIXBase):
 
 
 class WindowsPESection(_STIXBase):
-    _properties = {
-        'name': StringProperty(required=True),
-        'size': IntegerProperty(),
-        'entropy': FloatProperty(),
-        'hashes': HashesProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('name', StringProperty(required=True)),
+        ('size', IntegerProperty()),
+        ('entropy', FloatProperty()),
+        ('hashes', HashesProperty()),
+    ])
 
 
 class WindowsPEBinaryExt(_Extension):
-    _properties = {
-        'pe_type': StringProperty(required=True),  # open_vocab
-        'imphash': StringProperty(),
-        'machine_hex': HexProperty(),
-        'number_of_sections': IntegerProperty(),
-        'time_date_stamp': TimestampProperty(precision='second'),
-        'pointer_to_symbol_table_hex': HexProperty(),
-        'number_of_symbols': IntegerProperty(),
-        'size_of_optional_header': IntegerProperty(),
-        'characteristics_hex': HexProperty(),
-        'file_header_hashes': HashesProperty(),
-        'optional_header': EmbeddedObjectProperty(type=WindowsPEOptionalHeaderType),
-        'sections': ListProperty(EmbeddedObjectProperty(type=WindowsPESection)),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('pe_type', StringProperty(required=True)),  # open_vocab
+        ('imphash', StringProperty()),
+        ('machine_hex', HexProperty()),
+        ('number_of_sections', IntegerProperty()),
+        ('time_date_stamp', TimestampProperty(precision='second')),
+        ('pointer_to_symbol_table_hex', HexProperty()),
+        ('number_of_symbols', IntegerProperty()),
+        ('size_of_optional_header', IntegerProperty()),
+        ('characteristics_hex', HexProperty()),
+        ('file_header_hashes', HashesProperty()),
+        ('optional_header', EmbeddedObjectProperty(type=WindowsPEOptionalHeaderType)),
+        ('sections', ListProperty(EmbeddedObjectProperty(type=WindowsPESection))),
+    ])
 
 
 class File(_Observable):
     _type = 'file'
-    _properties = {
-        'type': TypeProperty(_type),
-        'extensions': ExtensionsProperty(enclosing_type=_type),
-        'hashes': HashesProperty(),
-        'size': IntegerProperty(),
-        'name': StringProperty(),
-        'name_enc': StringProperty(),
-        'magic_number_hex': HexProperty(),
-        'mime_type': StringProperty(),
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('extensions', ExtensionsProperty(enclosing_type=_type)),
+        ('hashes', HashesProperty()),
+        ('size', IntegerProperty()),
+        ('name', StringProperty()),
+        ('name_enc', StringProperty()),
+        ('magic_number_hex', HexProperty()),
+        ('mime_type', StringProperty()),
         # these are not the created/modified timestamps of the object itself
-        'created': TimestampProperty(),
-        'modified': TimestampProperty(),
-        'accessed': TimestampProperty(),
-        'parent_directory_ref': ObjectReferenceProperty(valid_types='directory'),
-        'is_encrypted': BooleanProperty(),
-        'encryption_algorithm': StringProperty(),
-        'decryption_key': StringProperty(),
-        'contains_refs': ListProperty(ObjectReferenceProperty),
-        'content_ref': ObjectReferenceProperty(valid_types='artifact'),
-    }
+        ('created', TimestampProperty()),
+        ('modified', TimestampProperty()),
+        ('accessed', TimestampProperty()),
+        ('parent_directory_ref', ObjectReferenceProperty(valid_types='directory')),
+        ('is_encrypted', BooleanProperty()),
+        ('encryption_algorithm', StringProperty()),
+        ('decryption_key', StringProperty()),
+        ('contains_refs', ListProperty(ObjectReferenceProperty)),
+        ('content_ref', ObjectReferenceProperty(valid_types='artifact')),
+    ])
 
     def _check_object_constraints(self):
         super(File, self)._check_object_constraints()
@@ -313,61 +331,68 @@ class File(_Observable):
 
 class IPv4Address(_Observable):
     _type = 'ipv4-addr'
-    _properties = {
-        'type': TypeProperty(_type),
-        'value': StringProperty(required=True),
-        'resolves_to_refs': ListProperty(ObjectReferenceProperty(valid_types='mac-addr')),
-        'belongs_to_refs': ListProperty(ObjectReferenceProperty(valid_types='autonomous-system')),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('value', StringProperty(required=True)),
+        ('resolves_to_refs', ListProperty(ObjectReferenceProperty(valid_types='mac-addr'))),
+        ('belongs_to_refs', ListProperty(ObjectReferenceProperty(valid_types='autonomous-system'))),
+    ])
 
 
 class IPv6Address(_Observable):
     _type = 'ipv6-addr'
-    _properties = {
-        'type': TypeProperty(_type),
-        'value': StringProperty(required=True),
-        'resolves_to_refs': ListProperty(ObjectReferenceProperty(valid_types='mac-addr')),
-        'belongs_to_refs': ListProperty(ObjectReferenceProperty(valid_types='autonomous-system')),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('value', StringProperty(required=True)),
+        ('resolves_to_refs', ListProperty(ObjectReferenceProperty(valid_types='mac-addr'))),
+        ('belongs_to_refs', ListProperty(ObjectReferenceProperty(valid_types='autonomous-system'))),
+    ])
 
 
 class MACAddress(_Observable):
     _type = 'mac-addr'
-    _properties = {
-        'type': TypeProperty(_type),
-        'value': StringProperty(required=True),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('value', StringProperty(required=True)),
+    ])
 
 
 class Mutex(_Observable):
     _type = 'mutex'
-    _properties = {
-        'type': TypeProperty(_type),
-        'name': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('name', StringProperty()),
+    ])
 
 
 class HTTPRequestExt(_Extension):
-    _properties = {
-        'request_method': StringProperty(required=True),
-        'request_value': StringProperty(required=True),
-        'request_version': StringProperty(),
-        'request_header': DictionaryProperty(),
-        'message_body_length': IntegerProperty(),
-        'message_body_data_ref': ObjectReferenceProperty(valid_types='artifact'),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('request_method', StringProperty(required=True)),
+        ('request_value', StringProperty(required=True)),
+        ('request_version', StringProperty()),
+        ('request_header', DictionaryProperty()),
+        ('message_body_length', IntegerProperty()),
+        ('message_body_data_ref', ObjectReferenceProperty(valid_types='artifact')),
+    ])
 
 
 class ICMPExt(_Extension):
-    _properties = {
-        'icmp_type_hex': HexProperty(required=True),
-        'icmp_code_hex': HexProperty(required=True),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('icmp_type_hex', HexProperty(required=True)),
+        ('icmp_code_hex', HexProperty(required=True)),
+    ])
 
 
 class SocketExt(_Extension):
-    _properties = {
-        'address_family': EnumProperty([
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('address_family', EnumProperty([
             "AF_UNSPEC",
             "AF_INET",
             "AF_IPX",
@@ -376,58 +401,60 @@ class SocketExt(_Extension):
             "AF_INET6",
             "AF_IRDA",
             "AF_BTH",
-        ], required=True),
-        'is_blocking': BooleanProperty(),
-        'is_listening': BooleanProperty(),
-        'protocol_family': EnumProperty([
+        ], required=True)),
+        ('is_blocking', BooleanProperty()),
+        ('is_listening', BooleanProperty()),
+        ('protocol_family', EnumProperty([
             "PF_INET",
             "PF_IPX",
             "PF_APPLETALK",
             "PF_INET6",
             "PF_AX25",
             "PF_NETROM"
-        ]),
-        'options': DictionaryProperty(),
-        'socket_type': EnumProperty([
+        ])),
+        ('options', DictionaryProperty()),
+        ('socket_type', EnumProperty([
             "SOCK_STREAM",
             "SOCK_DGRAM",
             "SOCK_RAW",
             "SOCK_RDM",
             "SOCK_SEQPACKET",
-        ]),
-    }
+        ])),
+    ])
 
 
 class TCPExt(_Extension):
-    _properties = {
-        'src_flags_hex': HexProperty(),
-        'dst_flags_hex': HexProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('src_flags_hex', HexProperty()),
+        ('dst_flags_hex', HexProperty()),
+    ])
 
 
 class NetworkTraffic(_Observable):
     _type = 'network-traffic'
-    _properties = {
-        'type': TypeProperty(_type),
-        'extensions': ExtensionsProperty(enclosing_type=_type),
-        'start': TimestampProperty(),
-        'end': TimestampProperty(),
-        'is_active': BooleanProperty(),
-        'src_ref': ObjectReferenceProperty(valid_types=['ipv4-addr', 'ipv6-addr', 'mac-addr', 'domain-name']),
-        'dst_ref': ObjectReferenceProperty(valid_types=['ipv4-addr', 'ipv6-addr', 'mac-addr', 'domain-name']),
-        'src_port': IntegerProperty(),
-        'dst_port': IntegerProperty(),
-        'protocols': ListProperty(StringProperty, required=True),
-        'src_byte_count': IntegerProperty(),
-        'dst_byte_count': IntegerProperty(),
-        'src_packets': IntegerProperty(),
-        'dst_packets': IntegerProperty(),
-        'ipfix': DictionaryProperty(),
-        'src_payload_ref': ObjectReferenceProperty(valid_types='artifact'),
-        'dst_payload_ref': ObjectReferenceProperty(valid_types='artifact'),
-        'encapsulates_refs': ListProperty(ObjectReferenceProperty(valid_types='network-traffic')),
-        'encapsulates_by_ref': ObjectReferenceProperty(valid_types='network-traffic'),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('extensions', ExtensionsProperty(enclosing_type=_type)),
+        ('start', TimestampProperty()),
+        ('end', TimestampProperty()),
+        ('is_active', BooleanProperty()),
+        ('src_ref', ObjectReferenceProperty(valid_types=['ipv4-addr', 'ipv6-addr', 'mac-addr', 'domain-name'])),
+        ('dst_ref', ObjectReferenceProperty(valid_types=['ipv4-addr', 'ipv6-addr', 'mac-addr', 'domain-name'])),
+        ('src_port', IntegerProperty()),
+        ('dst_port', IntegerProperty()),
+        ('protocols', ListProperty(StringProperty, required=True)),
+        ('src_byte_count', IntegerProperty()),
+        ('dst_byte_count', IntegerProperty()),
+        ('src_packets', IntegerProperty()),
+        ('dst_packets', IntegerProperty()),
+        ('ipfix', DictionaryProperty()),
+        ('src_payload_ref', ObjectReferenceProperty(valid_types='artifact')),
+        ('dst_payload_ref', ObjectReferenceProperty(valid_types='artifact')),
+        ('encapsulates_refs', ListProperty(ObjectReferenceProperty(valid_types='network-traffic'))),
+        ('encapsulates_by_ref', ObjectReferenceProperty(valid_types='network-traffic')),
+    ])
 
     def _check_object_constraints(self):
         super(NetworkTraffic, self)._check_object_constraints()
@@ -435,37 +462,39 @@ class NetworkTraffic(_Observable):
 
 
 class WindowsProcessExt(_Extension):
-    _properties = {
-        'aslr_enabled': BooleanProperty(),
-        'dep_enabled': BooleanProperty(),
-        'priority': StringProperty(),
-        'owner_sid': StringProperty(),
-        'window_title': StringProperty(),
-        'startup_info': DictionaryProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('aslr_enabled', BooleanProperty()),
+        ('dep_enabled', BooleanProperty()),
+        ('priority', StringProperty()),
+        ('owner_sid', StringProperty()),
+        ('window_title', StringProperty()),
+        ('startup_info', DictionaryProperty()),
+    ])
 
 
 class WindowsServiceExt(_Extension):
-    _properties = {
-        'service_name': StringProperty(required=True),
-        'descriptions': ListProperty(StringProperty),
-        'display_name': StringProperty(),
-        'group_name': StringProperty(),
-        'start_type': EnumProperty([
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('service_name', StringProperty(required=True)),
+        ('descriptions', ListProperty(StringProperty)),
+        ('display_name', StringProperty()),
+        ('group_name', StringProperty()),
+        ('start_type', EnumProperty([
             "SERVICE_AUTO_START",
             "SERVICE_BOOT_START",
             "SERVICE_DEMAND_START",
             "SERVICE_DISABLED",
             "SERVICE_SYSTEM_ALERT",
-        ]),
-        'service_dll_refs': ListProperty(ObjectReferenceProperty(valid_types='file')),
-        'service_type': EnumProperty([
+        ])),
+        ('service_dll_refs', ListProperty(ObjectReferenceProperty(valid_types='file'))),
+        ('service_type', EnumProperty([
             "SERVICE_KERNEL_DRIVER",
             "SERVICE_FILE_SYSTEM_DRIVER",
             "SERVICE_WIN32_OWN_PROCESS",
             "SERVICE_WIN32_SHARE_PROCESS",
-        ]),
-        'service_status': EnumProperty([
+        ])),
+        ('service_status', EnumProperty([
             "SERVICE_CONTINUE_PENDING",
             "SERVICE_PAUSE_PENDING",
             "SERVICE_PAUSED",
@@ -473,30 +502,31 @@ class WindowsServiceExt(_Extension):
             "SERVICE_START_PENDING",
             "SERVICE_STOP_PENDING",
             "SERVICE_STOPPED",
-        ]),
-    }
+        ])),
+    ])
 
 
 class Process(_Observable):
     _type = 'process'
-    _properties = {
-        'type': TypeProperty(_type),
-        'extensions': ExtensionsProperty(enclosing_type=_type),
-        'is_hidden': BooleanProperty(),
-        'pid': IntegerProperty(),
-        'name': StringProperty(),
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('extensions', ExtensionsProperty(enclosing_type=_type)),
+        ('is_hidden', BooleanProperty()),
+        ('pid', IntegerProperty()),
+        ('name', StringProperty()),
         # this is not the created timestamps of the object itself
-        'created': TimestampProperty(),
-        'cwd': StringProperty(),
-        'arguments': ListProperty(StringProperty),
-        'command_line': StringProperty(),
-        'environment_variables': DictionaryProperty(),
-        'opened_connection_refs': ListProperty(ObjectReferenceProperty(valid_types='network-traffic')),
-        'creator_user_ref': ObjectReferenceProperty(valid_types='user-account'),
-        'binary_ref': ObjectReferenceProperty(valid_types='file'),
-        'parent_ref': ObjectReferenceProperty(valid_types='process'),
-        'child_refs': ListProperty(ObjectReferenceProperty('process')),
-    }
+        ('created', TimestampProperty()),
+        ('cwd', StringProperty()),
+        ('arguments', ListProperty(StringProperty)),
+        ('command_line', StringProperty()),
+        ('environment_variables', DictionaryProperty()),
+        ('opened_connection_refs', ListProperty(ObjectReferenceProperty(valid_types='network-traffic'))),
+        ('creator_user_ref', ObjectReferenceProperty(valid_types='user-account')),
+        ('binary_ref', ObjectReferenceProperty(valid_types='file')),
+        ('parent_ref', ObjectReferenceProperty(valid_types='process')),
+        ('child_refs', ListProperty(ObjectReferenceProperty('process'))),
+    ])
 
     def _check_object_constraints(self):
         # no need to check windows-service-ext, since it has a required property
@@ -515,60 +545,65 @@ class Process(_Observable):
 
 class Software(_Observable):
     _type = 'software'
-    _properties = {
-        'type': TypeProperty(_type),
-        'name': StringProperty(required=True),
-        'cpe': StringProperty(),
-        'languages': ListProperty(StringProperty),
-        'vendor': StringProperty(),
-        'version': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('name', StringProperty(required=True)),
+        ('cpe', StringProperty()),
+        ('languages', ListProperty(StringProperty)),
+        ('vendor', StringProperty()),
+        ('version', StringProperty()),
+    ])
 
 
 class URL(_Observable):
     _type = 'url'
-    _properties = {
-        'type': TypeProperty(_type),
-        'value': StringProperty(required=True),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('value', StringProperty(required=True)),
+    ])
 
 
 class UNIXAccountExt(_Extension):
-    _properties = {
-        'gid': IntegerProperty(),
-        'groups': ListProperty(StringProperty),
-        'home_dir': StringProperty(),
-        'shell': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('gid', IntegerProperty()),
+        ('groups', ListProperty(StringProperty)),
+        ('home_dir', StringProperty()),
+        ('shell', StringProperty()),
+    ])
 
 
 class UserAccount(_Observable):
     _type = 'user-account'
-    _properties = {
-        'type': TypeProperty(_type),
-        'extensions': ExtensionsProperty(enclosing_type=_type),
-        'user_id': StringProperty(required=True),
-        'account_login': StringProperty(),
-        'account_type': StringProperty(),   # open vocab
-        'display_name': StringProperty(),
-        'is_service_account': BooleanProperty(),
-        'is_privileged': BooleanProperty(),
-        'can_escalate_privs': BooleanProperty(),
-        'is_disabled': BooleanProperty(),
-        'account_created': TimestampProperty(),
-        'account_expires': TimestampProperty(),
-        'password_last_changed': TimestampProperty(),
-        'account_first_login': TimestampProperty(),
-        'account_last_login': TimestampProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('extensions', ExtensionsProperty(enclosing_type=_type)),
+        ('user_id', StringProperty(required=True)),
+        ('account_login', StringProperty()),
+        ('account_type', StringProperty()),   # open vocab
+        ('display_name', StringProperty()),
+        ('is_service_account', BooleanProperty()),
+        ('is_privileged', BooleanProperty()),
+        ('can_escalate_privs', BooleanProperty()),
+        ('is_disabled', BooleanProperty()),
+        ('account_created', TimestampProperty()),
+        ('account_expires', TimestampProperty()),
+        ('password_last_changed', TimestampProperty()),
+        ('account_first_login', TimestampProperty()),
+        ('account_last_login', TimestampProperty()),
+    ])
 
 
 class WindowsRegistryValueType(_STIXBase):
     _type = 'windows-registry-value-type'
-    _properties = {
-        'name': StringProperty(required=True),
-        'data': StringProperty(),
-        'data_type': EnumProperty([
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('name', StringProperty(required=True)),
+        ('data', StringProperty()),
+        ('data_type', EnumProperty([
             'REG_NONE',
             'REG_SZ',
             'REG_EXPAND_SZ',
@@ -582,21 +617,22 @@ class WindowsRegistryValueType(_STIXBase):
             'REG_RESOURCE_REQUIREMENTS_LIST',
             'REG_QWORD',
             'REG_INVALID_TYPE',
-        ]),
-    }
+        ])),
+    ])
 
 
 class WindowsRegistryKey(_Observable):
     _type = 'windows-registry-key'
-    _properties = {
-        'type': TypeProperty(_type),
-        'key': StringProperty(required=True),
-        'values': ListProperty(EmbeddedObjectProperty(type=WindowsRegistryValueType)),
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('key', StringProperty(required=True)),
+        ('values', ListProperty(EmbeddedObjectProperty(type=WindowsRegistryValueType))),
         # this is not the modified timestamps of the object itself
-        'modified': TimestampProperty(),
-        'creator_user_ref': ObjectReferenceProperty(valid_types='user-account'),
-        'number_of_subkeys': IntegerProperty(),
-    }
+        ('modified', TimestampProperty()),
+        ('creator_user_ref', ObjectReferenceProperty(valid_types='user-account')),
+        ('number_of_subkeys', IntegerProperty()),
+    ])
 
     @property
     def values(self):
@@ -606,44 +642,46 @@ class WindowsRegistryKey(_Observable):
 
 class X509V3ExtenstionsType(_STIXBase):
     _type = 'x509-v3-extensions-type'
-    _properties = {
-        'basic_constraints': StringProperty(),
-        'name_constraints': StringProperty(),
-        'policy_constraints': StringProperty(),
-        'key_usage': StringProperty(),
-        'extended_key_usage': StringProperty(),
-        'subject_key_identifier': StringProperty(),
-        'authority_key_identifier': StringProperty(),
-        'subject_alternative_name': StringProperty(),
-        'issuer_alternative_name': StringProperty(),
-        'subject_directory_attributes': StringProperty(),
-        'crl_distribution_points': StringProperty(),
-        'inhibit_any_policy': StringProperty(),
-        'private_key_usage_period_not_before': TimestampProperty(),
-        'private_key_usage_period_not_after': TimestampProperty(),
-        'certificate_policies': StringProperty(),
-        'policy_mappings': StringProperty(),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('basic_constraints', StringProperty()),
+        ('name_constraints', StringProperty()),
+        ('policy_constraints', StringProperty()),
+        ('key_usage', StringProperty()),
+        ('extended_key_usage', StringProperty()),
+        ('subject_key_identifier', StringProperty()),
+        ('authority_key_identifier', StringProperty()),
+        ('subject_alternative_name', StringProperty()),
+        ('issuer_alternative_name', StringProperty()),
+        ('subject_directory_attributes', StringProperty()),
+        ('crl_distribution_points', StringProperty()),
+        ('inhibit_any_policy', StringProperty()),
+        ('private_key_usage_period_not_before', TimestampProperty()),
+        ('private_key_usage_period_not_after', TimestampProperty()),
+        ('certificate_policies', StringProperty()),
+        ('policy_mappings', StringProperty()),
+    ])
 
 
 class X509Certificate(_Observable):
     _type = 'x509-certificate'
-    _properties = {
-        'type': TypeProperty(_type),
-        'is_self_signed': BooleanProperty(),
-        'hashes': HashesProperty(),
-        'version': StringProperty(),
-        'serial_number': StringProperty(),
-        'signature_algorithm': StringProperty(),
-        'issuer': StringProperty(),
-        'validity_not_before': TimestampProperty(),
-        'validity_not_after': TimestampProperty(),
-        'subject': StringProperty(),
-        'subject_public_key_algorithm': StringProperty(),
-        'subject_public_key_modulus': StringProperty(),
-        'subject_public_key_exponent': IntegerProperty(),
-        'x509_v3_extensions': EmbeddedObjectProperty(type=X509V3ExtenstionsType),
-    }
+    _properties = OrderedDict()
+    _properties = _properties.update([
+        ('type', TypeProperty(_type)),
+        ('is_self_signed', BooleanProperty()),
+        ('hashes', HashesProperty()),
+        ('version', StringProperty()),
+        ('serial_number', StringProperty()),
+        ('signature_algorithm', StringProperty()),
+        ('issuer', StringProperty()),
+        ('validity_not_before', TimestampProperty()),
+        ('validity_not_after', TimestampProperty()),
+        ('subject', StringProperty()),
+        ('subject_public_key_algorithm', StringProperty()),
+        ('subject_public_key_modulus', StringProperty()),
+        ('subject_public_key_exponent', IntegerProperty()),
+        ('x509_v3_extensions', EmbeddedObjectProperty(type=X509V3ExtenstionsType)),
+    ])
 
 
 OBJ_MAP_OBSERVABLE = {
@@ -700,7 +738,7 @@ EXT_MAP = {
 }
 
 
-def parse_observable(data, _valid_refs=[], allow_custom=False):
+def parse_observable(data, _valid_refs, allow_custom=False):
     """Deserialize a string or file-like object into a STIX Cyber Observable object.
 
     Args:
@@ -739,17 +777,31 @@ def _register_observable(new_observable):
     OBJ_MAP_OBSERVABLE[new_observable._type] = new_observable
 
 
-def CustomObservable(type='x-custom-observable', properties={}):
+def CustomObservable(type='x-custom-observable', properties=None):
     """Custom STIX Cyber Observable type decorator
+
+    Example 1:
+
+    @CustomObservable('x-custom-observable', [
+        ('property1', StringProperty(required=True)),
+        ('property2', IntegerProperty()),
+    ])
+    class MyNewObservableType():
+        pass
     """
 
     def custom_builder(cls):
 
         class _Custom(cls, _Observable):
             _type = type
-            _properties = {
-                'type': TypeProperty(_type),
-            }
+            _properties = OrderedDict()
+            _properties = _properties.update([
+                ('type', TypeProperty(_type)),
+            ])
+
+            if not properties:
+                raise ValueError("Must supply a list, containing tuples. For example, [('property1', IntegerProperty())]")
+
             _properties.update(properties)
 
             def __init__(self, **kwargs):