diff --git a/doc/source/ch07_simulation.rst b/doc/source/ch07_simulation.rst
index 97a72c9f292f8cebfa19260f2d0f47eb9320306b..2a5ca5b24bb72b190c910adda8eb7866e1617d5f 100644
--- a/doc/source/ch07_simulation.rst
+++ b/doc/source/ch07_simulation.rst
@@ -43,6 +43,6 @@ Naming conventions
     >>>     r"L(?P<level>[0-9]+)_"
     >>>     r"(?P<version>[A-Z0-9]+).fits"
     >>> )
-    >>> mo = re.search(pattern, r"CSST_MSC_MS_SCI_20270626203558_20270626203828_100000066_01_L0_1.fits")
+    >>> mo = re.fullmatch(pattern, r"CSST_MSC_MS_SCI_20270626203558_20270626203828_100000066_01_L0_1.fits")
     >>> print(mo.groupdict())
     {'facility': 'MSC', 'project': 'MS', 'data_type': 'SCI', 't_start': '20260612100759', 't_stop': '20260612101029', 'obs_id': '100000036', 'detector': '16', 'level': '0', 'version': '1'}