diff --git a/stix2/v20/common.py b/stix2/v20/common.py
index c66b8f6..d574c92 100644
--- a/stix2/v20/common.py
+++ b/stix2/v20/common.py
@@ -1,6 +1,7 @@
 """STIX 2 Common Data Types and Properties."""
 
 from collections import OrderedDict
+import copy
 
 from ..base import _cls_init, _STIXBase
 from ..markings import _MarkingsMixin
@@ -124,6 +125,13 @@ class MarkingDefinition(_STIXBase, _MarkingsMixin):
             except KeyError:
                 raise ValueError("definition_type must be a valid marking type")
 
+            if marking_type == TLPMarking:
+                # TLP instances in the spec have millisecond precision unlike other markings
+                self._properties = copy.deepcopy(self._properties)
+                self._properties.update([
+                    ('created', TimestampProperty(default=lambda: NOW, precision='millisecond')),
+                ])
+
             if not isinstance(kwargs['definition'], marking_type):
                 defn = _get_dict(kwargs['definition'])
                 kwargs['definition'] = marking_type(**defn)

The instance of MarkingDefinition cannot pass validation because the 'created' property does't have millisecond.
Here is the screenshot:
![marking](https://user-images.githubusercontent.com/5939857/47416920-56c50f00-d7a9-11e8-87a7-aa9b1f82cdb7.PNG)

Source code:
![marking_class](https://user-images.githubusercontent.com/5939857/47417251-2af65900-d7aa-11e8-8914-5b1f0312bbb3.PNG)

Does the 'created' property should be
![property](https://user-images.githubusercontent.com/5939857/47417384-73ae1200-d7aa-11e8-86b3-7960130ca96f.PNG)
to pass validation?

diff --git a/stix2/test/test_markings.py b/stix2/test/test_markings.py
index ec8b664..49803f3 100644
--- a/stix2/test/test_markings.py
+++ b/stix2/test/test_markings.py
@@ -11,7 +11,7 @@ from .constants import MARKING_DEFINITION_ID
 EXPECTED_TLP_MARKING_DEFINITION = """{
     "type": "marking-definition",
     "id": "marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9",
-    "created": "2017-01-20T00:00:00Z",
+    "created": "2017-01-20T00:00:00.000Z",
     "definition_type": "tlp",
     "definition": {
         "tlp": "white"

pip install -e .[dev]
parse_log_pytest
requirements.txt
pytest
3.6
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
alabaster==0.7.13
antlr4-python3-runtime==4.9.3
async-generator==1.10
attrs==22.2.0
Babel==2.11.0
backcall==0.2.0
bleach==4.1.0
bump2version==1.0.1
bumpversion==0.6.0
certifi==2021.5.30
cfgv==3.3.1
charset-normalizer==2.0.12
coverage==6.2
decorator==5.1.1
defusedxml==0.7.1
distlib==0.3.9
docutils==0.18.1
entrypoints==0.4
filelock==3.4.1
identify==2.4.4
idna==3.10
imagesize==1.4.1
importlib-metadata==4.8.3
importlib-resources==5.2.3
iniconfig==1.1.1
ipython==7.16.3
ipython-genutils==0.2.0
jedi==0.17.2
Jinja2==3.0.3
jsonschema==3.2.0
jupyter-client==7.1.2
jupyter-core==4.9.2
jupyterlab-pygments==0.1.2
MarkupSafe==2.0.1
mistune==0.8.4
nbclient==0.5.9
nbconvert==6.0.7
nbformat==5.1.3
nbsphinx==0.3.2
nest-asyncio==1.6.0
nodeenv==1.6.0
packaging==21.3
pandocfilters==1.5.1
parso==0.7.1
pexpect==4.9.0
pickleshare==0.7.5
platformdirs==2.4.0
pluggy==1.0.0
pre-commit==2.17.0
prompt-toolkit==3.0.36
ptyprocess==0.7.0
py==1.11.0
Pygments==2.14.0
pyparsing==3.1.4
pyrsistent==0.18.0
pytest==7.0.1
pytest-cov==4.0.0
python-dateutil==2.9.0.post0
pytz==2025.2
PyYAML==6.0.1
pyzmq==25.1.2
requests==2.27.1
simplejson==3.20.1
six==1.17.0
snowballstemmer==2.2.0
Sphinx==1.5.6
sphinx-prompt==1.5.0
-e git+https://github.com/oasis-open/cti-python-stix2.git@6613b55a433d4278c46f51327569fce0f125724c#egg=stix2
stix2-patterns==2.0.0
testpath==0.6.0
toml==0.10.2
tomli==1.2.3
tornado==6.1
tox==3.28.0
traitlets==4.3.3
typing_extensions==4.1.1
urllib3==1.26.20
virtualenv==20.16.2
wcwidth==0.2.13
webencodings==0.5.1
zipp==3.6.0

name: cti-python-stix2
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=21.2.2=py36h06a4308_0
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - alabaster==0.7.13
      - antlr4-python3-runtime==4.9.3
      - async-generator==1.10
      - attrs==22.2.0
      - babel==2.11.0
      - backcall==0.2.0
      - bleach==4.1.0
      - bump2version==1.0.1
      - bumpversion==0.6.0
      - cfgv==3.3.1
      - charset-normalizer==2.0.12
      - coverage==6.2
      - decorator==5.1.1
      - defusedxml==0.7.1
      - distlib==0.3.9
      - docutils==0.18.1
      - entrypoints==0.4
      - filelock==3.4.1
      - identify==2.4.4
      - idna==3.10
      - imagesize==1.4.1
      - importlib-metadata==4.8.3
      - importlib-resources==5.2.3
      - iniconfig==1.1.1
      - ipython==7.16.3
      - ipython-genutils==0.2.0
      - jedi==0.17.2
      - jinja2==3.0.3
      - jsonschema==3.2.0
      - jupyter-client==7.1.2
      - jupyter-core==4.9.2
      - jupyterlab-pygments==0.1.2
      - markupsafe==2.0.1
      - mistune==0.8.4
      - nbclient==0.5.9
      - nbconvert==6.0.7
      - nbformat==5.1.3
      - nbsphinx==0.3.2
      - nest-asyncio==1.6.0
      - nodeenv==1.6.0
      - packaging==21.3
      - pandocfilters==1.5.1
      - parso==0.7.1
      - pexpect==4.9.0
      - pickleshare==0.7.5
      - platformdirs==2.4.0
      - pluggy==1.0.0
      - pre-commit==2.17.0
      - prompt-toolkit==3.0.36
      - ptyprocess==0.7.0
      - py==1.11.0
      - pygments==2.14.0
      - pyparsing==3.1.4
      - pyrsistent==0.18.0
      - pytest==7.0.1
      - pytest-cov==4.0.0
      - python-dateutil==2.9.0.post0
      - pytz==2025.2
      - pyyaml==6.0.1
      - pyzmq==25.1.2
      - requests==2.27.1
      - simplejson==3.20.1
      - six==1.17.0
      - snowballstemmer==2.2.0
      - sphinx==1.5.6
      - sphinx-prompt==1.5.0
      - stix2-patterns==2.0.0
      - testpath==0.6.0
      - toml==0.10.2
      - tomli==1.2.3
      - tornado==6.1
      - tox==3.28.0
      - traitlets==4.3.3
      - typing-extensions==4.1.1
      - urllib3==1.26.20
      - virtualenv==20.16.2
      - wcwidth==0.2.13
      - webencodings==0.5.1
      - zipp==3.6.0
prefix: /opt/conda/envs/cti-python-stix2

stix2/test/test_markings.py::test_marking_def_example_with_tlp
stix2/test/test_markings.py::test_marking_def_example_with_statement_positional_argument stix2/test/test_markings.py::test_marking_def_example_with_kwargs_statement stix2/test/test_markings.py::test_marking_def_invalid_type stix2/test/test_markings.py::test_campaign_with_markings_example stix2/test/test_markings.py::test_granular_example stix2/test/test_markings.py::test_granular_example_with_bad_selector stix2/test/test_markings.py::test_campaign_with_granular_markings_example stix2/test/test_markings.py::test_parse_marking_definition[{\n stix2/test/test_markings.py::test_parse_marking_definition[data1] stix2/test/test_markings.py::test_registered_custom_marking stix2/test/test_markings.py::test_registered_custom_marking_raises_exception stix2/test/test_markings.py::test_not_registered_marking_raises_exception stix2/test/test_markings.py::test_marking_wrong_type_construction stix2/test/test_markings.py::test_campaign_add_markings
stix2/v20/common.py
stix2/v20/common.py