diff --git a/src/_pytest/hookspec.py b/src/_pytest/hookspec.py
index 446f580ee..143ec190c 100644
--- a/src/_pytest/hookspec.py
+++ b/src/_pytest/hookspec.py
@@ -505,7 +505,9 @@ def pytest_runtest_logstart(
     See :hook:`pytest_runtest_protocol` for a description of the runtest protocol.
 
     :param nodeid: Full node ID of the item.
-    :param location: A tuple of ``(filename, lineno, testname)``.
+    :param location: A tuple of ``(filename, lineno, testname)``
+        where ``filename`` is a file path relative to ``config.rootpath``
+        and ``lineno`` is 0-based.
     """
 
 
@@ -517,7 +519,9 @@ def pytest_runtest_logfinish(
     See :hook:`pytest_runtest_protocol` for a description of the runtest protocol.
 
     :param nodeid: Full node ID of the item.
-    :param location: A tuple of ``(filename, lineno, testname)``.
+    :param location: A tuple of ``(filename, lineno, testname)``
+        where ``filename`` is a file path relative to ``config.rootpath``
+        and ``lineno`` is 0-based.
     """
 
 
diff --git a/src/_pytest/nodes.py b/src/_pytest/nodes.py
index cfb9b5a36..c74740dbc 100644
--- a/src/_pytest/nodes.py
+++ b/src/_pytest/nodes.py
@@ -511,7 +511,7 @@ def get_fslocation_from_item(node: "Node") -> Tuple[Union[str, Path], Optional[i
     * "obj": a Python object that the node wraps.
     * "fspath": just a path
 
-    :rtype: A tuple of (str|Path, int) with filename and line number.
+    :rtype: A tuple of (str|Path, int) with filename and 0-based line number.
     """
     # See Item.location.
     location: Optional[Tuple[str, Optional[int], str]] = getattr(node, "location", None)
@@ -755,7 +755,7 @@ class Item(Node):
         Returns a tuple with three elements:
 
         - The path of the test (default ``self.path``)
-        - The line number of the test (default ``None``)
+        - The 0-based line number of the test (default ``None``)
         - A name of the test to be shown (default ``""``)
 
         .. seealso:: :ref:`non-python tests`
@@ -764,6 +764,11 @@ class Item(Node):
 
     @cached_property
     def location(self) -> Tuple[str, Optional[int], str]:
+        """
+        Returns a tuple of ``(relfspath, lineno, testname)`` for this item
+        where ``relfspath`` is file path relative to ``config.rootpath``
+        and lineno is a 0-based line number.
+        """
         location = self.reportinfo()
         path = absolutepath(os.fspath(location[0]))
         relfspath = self.session._node_location_to_relpath(path)
diff --git a/src/_pytest/reports.py b/src/_pytest/reports.py
index a8fa61787..2e36514ea 100644
--- a/src/_pytest/reports.py
+++ b/src/_pytest/reports.py
@@ -273,6 +273,8 @@ class TestReport(BaseReport):
         #: A (filesystempath, lineno, domaininfo) tuple indicating the
         #: actual location of a test item - it might be different from the
         #: collected one e.g. if a method is inherited from a different module.
+        #: The filesystempath may be relative to ``config.rootdir``.
+        #: The line number is 0-based.
         self.location: Tuple[str, Optional[int], str] = location
 
         #: A name -> value dictionary containing all keywords and
@@ -417,7 +419,9 @@ class CollectReport(BaseReport):
         self.__dict__.update(extra)
 
     @property
-    def location(self):
+    def location(  # type:ignore[override]
+        self,
+    ) -> Optional[Tuple[str, Optional[int], str]]:
         return (self.fspath, None, self.fspath)
 
     def __repr__(self) -> str:
diff --git a/testing/test_runner.py b/testing/test_runner.py
index c6d5b8aaf..de3e18184 100644
--- a/testing/test_runner.py
+++ b/testing/test_runner.py
@@ -473,6 +473,7 @@ class TestSessionReports:
         assert not rep.skipped
         assert rep.passed
         locinfo = rep.location
+        assert locinfo is not None
         assert locinfo[0] == col.path.name
         assert not locinfo[1]
         assert locinfo[2] == col.path.name