diff --git a/src/calibre/db/backend.py b/src/calibre/db/backend.py
index cc90ceb1f2..75e381f89d 100644
--- a/src/calibre/db/backend.py
+++ b/src/calibre/db/backend.py
@@ -60,6 +60,7 @@ COVER_FILE_NAME = 'cover.jpg'
 METADATA_FILE_NAME = 'metadata.opf'
 DEFAULT_TRASH_EXPIRY_TIME_SECONDS = 14 * 86400
 TRASH_DIR_NAME =  '.caltrash'
+DATA_DIR_NAME = 'data'
 BOOK_ID_PATH_TEMPLATE = ' ({})'
 CUSTOM_DATA_TYPES = frozenset(('rating', 'text', 'comments', 'datetime',
     'int', 'float', 'bool', 'series', 'composite', 'enumeration'))
diff --git a/src/calibre/ebooks/metadata/book/render.py b/src/calibre/ebooks/metadata/book/render.py
index 7c16fdab53..f5400ce73f 100644
--- a/src/calibre/ebooks/metadata/book/render.py
+++ b/src/calibre/ebooks/metadata/book/render.py
@@ -5,18 +5,21 @@ __license__ = 'GPL v3'
 __copyright__ = '2014, Kovid Goyal <kovid at kovidgoyal.net>'
 
 import os
-from functools import partial
 from contextlib import suppress
+from functools import partial
 
-from calibre import prepare_string_for_xml, force_unicode
-from calibre.ebooks.metadata import fmt_sidx, rating_to_stars
-from calibre.ebooks.metadata.search_internet import name_for, url_for_author_search, url_for_book_search, qquote, DEFAULT_AUTHOR_SOURCE
-from calibre.ebooks.metadata.sources.identify import urls_from_identifiers
+from calibre import force_unicode, prepare_string_for_xml
 from calibre.constants import filesystem_encoding
+from calibre.db.backend import DATA_DIR_NAME
+from calibre.ebooks.metadata import fmt_sidx, rating_to_stars
+from calibre.ebooks.metadata.search_internet import (
+    DEFAULT_AUTHOR_SOURCE, name_for, qquote, url_for_author_search, url_for_book_search,
+)
+from calibre.ebooks.metadata.sources.identify import urls_from_identifiers
 from calibre.library.comments import comments_to_html, markdown
-from calibre.utils.icu import sort_key
+from calibre.utils.date import format_date, is_date_undefined
 from calibre.utils.formatter import EvalFormatter
-from calibre.utils.date import is_date_undefined, format_date
+from calibre.utils.icu import sort_key
 from calibre.utils.localization import calibre_langcode_to_name
 from calibre.utils.serialize import json_dumps
 from polyglot.binary import as_hex_unicode
@@ -213,7 +216,7 @@ def mi_to_html(
                     link = '<a href="{}" title="{}">{}</a>{}'.format(action(scheme, book_id=book_id, loc=loc),
                         prepare_string_for_xml(path, True), _('Click to open'), extra)
                     if not isdevice:
-                        data_path = os.path.join(path, 'data')
+                        data_path = os.path.join(path, DATA_DIR_NAME)
                         with suppress(OSError):
                             if os.listdir(data_path):
                                 link += ' \xa0 <a href="{}" title="{}">{}</a>'.format(
diff --git a/src/calibre/gui2/actions/view.py b/src/calibre/gui2/actions/view.py
index f949547dd0..738e6770e5 100644
--- a/src/calibre/gui2/actions/view.py
+++ b/src/calibre/gui2/actions/view.py
@@ -9,12 +9,13 @@ import json
 import os
 import time
 from functools import partial
-from qt.core import QAction, QIcon, pyqtSignal, QDialog
+from qt.core import QAction, QDialog, QIcon, pyqtSignal
 
 from calibre.constants import ismacos, iswindows
+from calibre.db.backend import DATA_DIR_NAME
 from calibre.gui2 import (
     Dispatcher, config, elided_text, error_dialog, info_dialog, open_local_file,
-    question_dialog
+    question_dialog,
 )
 from calibre.gui2.actions import InterfaceAction
 from calibre.gui2.dialogs.choose_format import ChooseFormatDialog
@@ -283,7 +284,7 @@ class ViewAction(InterfaceAction):
 
     def view_data_folder_for_id(self, id_):
         path = self.gui.library_view.model().db.abspath(id_, index_is_id=True)
-        open_local_file(os.path.join(path, 'data'))
+        open_local_file(os.path.join(path, DATA_DIR_NAME))
 
     def view_book(self, triggered):
         rows = self.gui.current_view().selectionModel().selectedRows()
diff --git a/src/calibre/gui2/book_details.py b/src/calibre/gui2/book_details.py
index fc369d437c..0eade46865 100644
--- a/src/calibre/gui2/book_details.py
+++ b/src/calibre/gui2/book_details.py
@@ -15,6 +15,7 @@ from qt.core import (
 
 from calibre import fit_image, sanitize_file_name
 from calibre.constants import config_dir, iswindows
+from calibre.db.backend import DATA_DIR_NAME
 from calibre.ebooks import BOOK_EXTENSIONS
 from calibre.ebooks.metadata.book.base import Metadata, field_metadata
 from calibre.ebooks.metadata.book.render import mi_to_html
@@ -476,7 +477,7 @@ def create_copy_links(menu, data=None):
     link(_('Link to show book in calibre'), f'calibre://show-book/{library_id}/{book_id}')
     link(_('Link to show book details in a popup window'), f'calibre://book-details/{library_id}/{book_id}')
     mi = db.new_api.get_proxy_metadata(book_id)
-    data_path = os.path.join(db.backend.library_path, mi.path, 'data')
+    data_path = os.path.join(db.backend.library_path, mi.path, DATA_DIR_NAME)
     with suppress(OSError):
         if os.listdir(data_path):
             if iswindows:
diff --git a/src/calibre/gui2/comments_editor.py b/src/calibre/gui2/comments_editor.py
index 5fbd0dd042..2761e89f30 100644
--- a/src/calibre/gui2/comments_editor.py
+++ b/src/calibre/gui2/comments_editor.py
@@ -19,6 +19,7 @@ from qt.core import (
 )
 
 from calibre import xml_replace_entities
+from calibre.db.backend import DATA_DIR_NAME
 from calibre.ebooks.chardet import xml_to_unicode
 from calibre.gui2 import (
     NO_URL_FORMATTING, choose_dir, choose_files, error_dialog, gprefs, is_dark_theme,
@@ -707,7 +708,7 @@ class EditorWidget(QTextEdit, LineEditECM):  # {{{
         d.bb = QDialogButtonBox(QDialogButtonBox.StandardButton.Ok|QDialogButtonBox.StandardButton.Cancel)
         d.br = b = QPushButton(_('&File'))
         base = os.path.dirname(self.base_url.toLocalFile()) if self.base_url else os.getcwd()
-        data_path = os.path.join(base, 'data')
+        data_path = os.path.join(base, DATA_DIR_NAME)
         if self.base_url:
             os.makedirs(data_path, exist_ok=True)
 
diff --git a/src/calibre/library/check_library.py b/src/calibre/library/check_library.py
index eb5778a819..655e5599e8 100644
--- a/src/calibre/library/check_library.py
+++ b/src/calibre/library/check_library.py
@@ -12,13 +12,15 @@ import traceback
 
 from calibre import isbytestring
 from calibre.constants import filesystem_encoding
-from calibre.db.backend import COVER_FILE_NAME, METADATA_FILE_NAME, TRASH_DIR_NAME
+from calibre.db.backend import (
+    COVER_FILE_NAME, DATA_DIR_NAME, METADATA_FILE_NAME, TRASH_DIR_NAME,
+)
 from calibre.ebooks import BOOK_EXTENSIONS
 from calibre.utils.localization import _
 from polyglot.builtins import iteritems
 
 EBOOK_EXTENSIONS = frozenset(BOOK_EXTENSIONS)
-NORMALS = frozenset({METADATA_FILE_NAME, COVER_FILE_NAME, 'data'})
+NORMALS = frozenset({METADATA_FILE_NAME, COVER_FILE_NAME, DATA_DIR_NAME})
 IGNORE_AT_TOP_LEVEL = frozenset({'metadata.db', 'metadata_db_prefs_backup.json', 'metadata_pre_restore.db', 'full-text-search.db', TRASH_DIR_NAME})
 
 '''