diff --git a/src/ifcopenshell-python/ifcopenshell/api/alignment/__init__.py b/src/ifcopenshell-python/ifcopenshell/api/alignment/__init__.py
index 56a158842c..e0d5684164 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/alignment/__init__.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/alignment/__init__.py
@@ -25,7 +25,7 @@ are automatically created and maintained.
 
 Alignments are created with stationing referents. Each layout segment is assigned a position referent that informs about
 the start point of the segment. An example is the point of curvature of a horizontal circular curve. The referent is
-nested to the segment representing the circular arc and is named with a indicator of the position and the station, e.g. "P.C. (145+98.32)"
+nested to the segment representing the circular arc and is named with the alignment name and an indicator of the position and the station, e.g. "MyAlignment 145+98.32 (P.C.)"
 
 This API does not determine alignment parameters based on rules, such as minimum curve radius as a function of design speed or sight distance.
 
@@ -89,6 +89,7 @@ from .layout_vertical_alignment_by_pi_method import (
     layout_vertical_alignment_by_pi_method,
 )
 from .name_segments import name_segments
+from .update_alignment_parameter_segment_tags import update_alignment_parameter_segment_tags
 from .update_end_point import update_end_point
 from .update_fallback_position import update_fallback_position
 from .update_key_point_referents import update_key_point_referents
@@ -132,6 +133,7 @@ __all__ = [
     "layout_vertical_alignment_by_pi_method",
     "name_segments",
     "register_referent_name_callback",
+    "update_alignment_parameter_segment_tags",
     "update_end_point",
     "update_fallback_position",
     "update_key_point_referents",
diff --git a/src/ifcopenshell-python/ifcopenshell/api/alignment/_get_key_point_tag.py b/src/ifcopenshell-python/ifcopenshell/api/alignment/_get_key_point_tag.py
new file mode 100644
index 0000000000..ca888f2e9c
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/alignment/_get_key_point_tag.py
@@ -0,0 +1,30 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import ifcopenshell
+import ifcopenshell.util.alignment
+
+
+def _get_key_point_tag(file: ifcopenshell.file, label: str, station: float) -> str:
+    """
+    Builds the station-and-label text shared by update_alignment_parameter_segment_tags (used
+    directly as IfcAlignmentParameterSegment.StartTag/EndTag) and update_key_point_referents (used,
+    prefixed with the alignment name, as IfcReferent.Name): "<station> (<label>)", e.g.
+    "145+98.32 (P.O.B.)".
+    """
+    return f"{ifcopenshell.util.alignment.station_as_string(file, station)} ({label})"
diff --git a/src/ifcopenshell-python/ifcopenshell/api/alignment/update_alignment_parameter_segment_tags.py b/src/ifcopenshell-python/ifcopenshell/api/alignment/update_alignment_parameter_segment_tags.py
new file mode 100644
index 0000000000..9a72b19d49
--- /dev/null
+++ b/src/ifcopenshell-python/ifcopenshell/api/alignment/update_alignment_parameter_segment_tags.py
@@ -0,0 +1,100 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import ifcopenshell
+import ifcopenshell.api.alignment
+from ifcopenshell import entity_instance
+from ifcopenshell.api.alignment._get_key_point_tag import _get_key_point_tag
+from ifcopenshell.api.alignment._get_segment_start_point_label import (
+    _get_segment_start_point_label,
+)
+
+
+def update_alignment_parameter_segment_tags(file: ifcopenshell.file, layout: entity_instance) -> None:
+    """
+    Sets IfcAlignmentParameterSegment.StartTag/EndTag for every segment transition in an alignment
+    layout. Unlike update_key_point_referents, this does not create any IfcReferent or IfcRelNests --
+    it only mutates the StartTag/EndTag string attributes already present on each segment's
+    DesignParameters.
+
+    For each transition between two consecutive segments, the outgoing segment's EndTag and the
+    incoming segment's StartTag are both set to the same computed tag (they describe the same
+    physical point), using the same label-and-station format as update_key_point_referents' Name
+    minus the alignment name (via _get_key_point_tag), e.g. "145+98.32 (P.C.)". Every real segment
+    ends up with both StartTag and EndTag populated: the first segment's StartTag and the last
+    segment's EndTag come from the "Beginning of Alignment"/"End of Alignment" boundary labels.
+
+    Labels come from _get_segment_start_point_label -- if a callback has been registered via
+    register_referent_name_callback(), its output is used instead of the built-in labels, exactly as
+    in update_key_point_referents.
+
+    :param layout: IfcAlignmentHorizontal, IfcAlignmentVertical, or IfcAlignmentCant
+    :return: None -- this function mutates segment.DesignParameters.StartTag/EndTag in place
+
+    Example:
+
+    .. code:: python
+
+        horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+        ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(model, horizontal)
+    """
+
+    expected_types = ["IfcAlignmentHorizontal", "IfcAlignmentVertical", "IfcAlignmentCant"]
+    if not layout.is_a() in expected_types:
+        raise TypeError(
+            f"Expected entity type to be one of {[_ for _ in expected_types]}, instead received {layout.is_a()}"
+        )
+
+    alignment = ifcopenshell.api.alignment.get_alignment(layout)
+    if alignment is None:
+        raise ValueError(f"{layout.is_a()} #{layout.id()} is not nested under an IfcAlignment.")
+
+    segments = list(ifcopenshell.api.alignment.get_layout_segments(layout))
+    if segments and ifcopenshell.api.alignment.has_zero_length_segment(layout):
+        segments = segments[:-1]
+
+    if not segments:
+        return
+
+    start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
+    is_horizontal = layout.is_a("IfcAlignmentHorizontal")
+
+    distance_along = 0.0
+    prev_segment = None
+    for segment in segments:
+        dp = segment.DesignParameters
+        seg_distance_along = distance_along if is_horizontal else dp.StartDistAlong
+
+        label = _get_segment_start_point_label(prev_segment, segment)
+        station = start_station + seg_distance_along
+        tag = _get_key_point_tag(file, label, station)
+
+        dp.StartTag = tag
+        if prev_segment is not None:
+            prev_segment.DesignParameters.EndTag = tag
+
+        if is_horizontal:
+            distance_along += dp.SegmentLength
+        else:
+            distance_along = dp.StartDistAlong + dp.HorizontalLength
+
+        prev_segment = segment
+
+    label = _get_segment_start_point_label(prev_segment, None)
+    station = start_station + distance_along
+    prev_segment.DesignParameters.EndTag = _get_key_point_tag(file, label, station)
diff --git a/src/ifcopenshell-python/ifcopenshell/api/alignment/update_key_point_referents.py b/src/ifcopenshell-python/ifcopenshell/api/alignment/update_key_point_referents.py
index 6d5bd37ac0..9ad933ef26 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/alignment/update_key_point_referents.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/alignment/update_key_point_referents.py
@@ -22,9 +22,9 @@ import ifcopenshell
 import ifcopenshell.api.alignment
 import ifcopenshell.api.pset
 import ifcopenshell.guid
-import ifcopenshell.util.alignment
 import ifcopenshell.util.element
 from ifcopenshell import entity_instance
+from ifcopenshell.api.alignment._get_key_point_tag import _get_key_point_tag
 from ifcopenshell.api.alignment._get_segment_start_point_label import (
     _get_segment_start_point_label,
 )
@@ -76,7 +76,7 @@ def _create_key_point_referent(
             ),
         )
 
-    name = f"{label} ({ifcopenshell.util.alignment.station_as_string(file, station)})"
+    name = f"{alignment.Name} {_get_key_point_tag(file, label, station)}"
 
     referent = file.createIfcReferent(
         GlobalId=ifcopenshell.guid.new(),
@@ -105,7 +105,8 @@ def update_key_point_referents(
     Creates IfcReferent key-point markers for every segment transition in an alignment layout.
 
     Labels are derived from _get_segment_start_point_label (e.g. "P.C.", "P.T.", "P.O.B.",
-    "P.V.C.", ...), with the station appended, e.g. "P.C. (145+98.32)". Different jurisdictions use
+    "P.V.C.", ...), and combined with the alignment name and station to build the Name, e.g.
+    "MyAlignment 145+98.32 (P.C.)". Different jurisdictions use
     different naming systems for these key points -- register_referent_name_callback() lets a
     caller override the default horizontal/vertical/cant labeling before calling this function; if
     a callback is registered, its output is used here instead of the built-in labels. Referents are
@@ -145,7 +146,7 @@ def update_key_point_referents(
         ifcopenshell.api.alignment.register_referent_name_callback(horizontal=my_horizontal_labels)
         horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
         nest = ifcopenshell.api.alignment.update_key_point_referents(model, horizontal)
-        # nest.RelatedObjects[0].Name starts with "Start (" instead of the default "P.O.B. ("
+        # nest.RelatedObjects[0].Name ends with "(Start)" instead of the default "(P.O.B.)"
     """
 
     expected_types = ["IfcAlignmentHorizontal", "IfcAlignmentVertical", "IfcAlignmentCant"]
diff --git a/src/ifcopenshell-python/test/api/alignment/test_referent_names.py b/src/ifcopenshell-python/test/api/alignment/test_referent_names.py
index 856e1ad197..6f9ad7faf4 100644
--- a/src/ifcopenshell-python/test/api/alignment/test_referent_names.py
+++ b/src/ifcopenshell-python/test/api/alignment/test_referent_names.py
@@ -96,6 +96,10 @@ def callback_alignment():
     yield alignment
 
 
+def _label(name):
+    return name.rsplit("(", 1)[1].rstrip(")")
+
+
 def test_with_default_names(default_names_alignment):
     file = default_names_alignment.file
     horizontal = ifcopenshell.api.alignment.get_horizontal_layout(default_names_alignment)
@@ -107,8 +111,8 @@ def test_with_default_names(default_names_alignment):
     expected_h = ["P.O.B.", "P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T.", "P.O.E."]
     expected_v = ["V.P.O.B.", "P.V.C.", "P.V.T.", "P.V.C.", "P.V.T.", "P.V.C.", "P.V.T.", "P.V.C.", "P.V.T.", "V.P.O.E."]
 
-    assert [r.Name.split(" (")[0] for r in h_nest.RelatedObjects] == expected_h
-    assert [r.Name.split(" (")[0] for r in v_nest.RelatedObjects] == expected_v
+    assert [_label(r.Name) for r in h_nest.RelatedObjects] == expected_h
+    assert [_label(r.Name) for r in v_nest.RelatedObjects] == expected_v
 
 
 def test_with_callbacks(callback_alignment):
@@ -122,7 +126,7 @@ def test_with_callbacks(callback_alignment):
     expected_h = ["A", "Q", "Q", "Q", "Q", "Q", "Q", "Z"]
     expected_v = ["a", "q", "q", "q", "q", "q", "q", "q", "q", "z"]
 
-    assert [r.Name.split(" (")[0] for r in h_nest.RelatedObjects] == expected_h
-    assert [r.Name.split(" (")[0] for r in v_nest.RelatedObjects] == expected_v
+    assert [_label(r.Name) for r in h_nest.RelatedObjects] == expected_h
+    assert [_label(r.Name) for r in v_nest.RelatedObjects] == expected_v
 
     ifcopenshell.api.alignment.register_referent_name_callback(None, None, None)  # reset global state
diff --git a/src/ifcopenshell-python/test/api/alignment/test_update_alignment_parameter_segment_tags.py b/src/ifcopenshell-python/test/api/alignment/test_update_alignment_parameter_segment_tags.py
new file mode 100644
index 0000000000..daaeaf062a
--- /dev/null
+++ b/src/ifcopenshell-python/test/api/alignment/test_update_alignment_parameter_segment_tags.py
@@ -0,0 +1,279 @@
+# IfcOpenShell - IFC toolkit and geometry engine
+# Copyright (C) 2025 Thomas Krijnen <thomas@aecgeeks.com>
+#
+# This file is part of IfcOpenShell.
+#
+# IfcOpenShell is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Lesser General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# IfcOpenShell is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with IfcOpenShell.  If not, see <http://www.gnu.org/licenses/>.
+
+import pytest
+
+import ifcopenshell.api.alignment
+import ifcopenshell.api.context
+import ifcopenshell.api.unit
+import ifcopenshell.util.alignment
+
+COORDINATES = [(500.0, 2500.0), (3340.0, 660.0), (4340.0, 5000.0), (7600.0, 4560.0), (8480.0, 2010.0)]
+RADII = [1000.0, 1250.0, 950.0]
+VPOINTS = [(0.0, 100.0), (2000.0, 135.0), (5000.0, 105.0), (7400.0, 153.0), (9800.0, 105.0), (12800.0, 90.0)]
+LENGTHS = [1600.0, 1200.0, 2000.0, 800.0]
+
+
+def _new_file():
+    file = ifcopenshell.file(schema="IFC4X3")
+    file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_si_unit(file, unit_type="LENGTHUNIT")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    geometric_representation_context = ifcopenshell.api.context.add_context(file, context_type="Model")
+    ifcopenshell.api.context.add_context(
+        file,
+        context_type="Model",
+        context_identifier="Axis",
+        target_view="MODEL_VIEW",
+        parent=geometric_representation_context,
+    )
+    return file
+
+
+def _new_file_no_context():
+    file = ifcopenshell.file(schema="IFC4X3")
+    file.createIfcProject(GlobalId=ifcopenshell.guid.new(), Name="Test")
+    length = ifcopenshell.api.unit.add_si_unit(file, unit_type="LENGTHUNIT")
+    ifcopenshell.api.unit.assign_unit(file, units=[length])
+    return file
+
+
+def _build_alignment(file, start_station=0.0):
+    return ifcopenshell.api.alignment.create_by_pi_method(
+        file, "TestAlignment", COORDINATES, RADII, VPOINTS, LENGTHS, start_station
+    )
+
+
+def _real_segments(layout):
+    segments = ifcopenshell.api.alignment.get_layout_segments(layout)
+    return segments[:-1] if ifcopenshell.api.alignment.has_zero_length_segment(layout) else segments
+
+
+def _label(tag):
+    return tag.rsplit("(", 1)[1].rstrip(")")
+
+
+def test_wrong_layout_type_raises_type_error():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    with pytest.raises(TypeError):
+        ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, alignment)
+
+
+def test_not_nested_under_alignment_raises_value_error():
+    file = _new_file_no_context()
+    horizontal = file.createIfcAlignmentHorizontal(GlobalId=ifcopenshell.guid.new())
+    with pytest.raises(ValueError):
+        ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+
+def test_returns_none():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    result = ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    assert result is None
+
+
+def test_no_referents_or_rel_nests_created():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    referents_before = len(file.by_type("IfcReferent"))
+    rel_nests_before = len(file.by_type("IfcRelNests"))
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    assert len(file.by_type("IfcReferent")) == referents_before
+    assert len(file.by_type("IfcRelNests")) == rel_nests_before
+
+
+def test_no_real_segments_leaves_tags_none():
+    file = _new_file_no_context()
+    alignment = ifcopenshell.api.alignment.create(file, "A1", include_geometry=False)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    result = ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    assert result is None
+    segments = ifcopenshell.api.alignment.get_layout_segments(horizontal)
+    assert len(segments) == 1  # only the auto zero-length segment
+    assert segments[0].DesignParameters.StartTag is None
+    assert segments[0].DesignParameters.EndTag is None
+
+
+def test_single_real_segment_produces_only_boundary_tags():
+    file = _new_file_no_context()
+    alignment = ifcopenshell.api.alignment.create(file, "A1", include_geometry=False)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    design_parameters = file.createIfcAlignmentHorizontalSegment(
+        StartTag=None,
+        EndTag=None,
+        StartPoint=file.createIfcCartesianPoint((0.0, 0.0)),
+        StartDirection=0.0,
+        StartRadiusOfCurvature=0.0,
+        EndRadiusOfCurvature=0.0,
+        SegmentLength=100.0,
+        GravityCenterLineHeight=None,
+        PredefinedType="LINE",
+    )
+    ifcopenshell.api.alignment.create_layout_segment(file, horizontal, design_parameters)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    segments = _real_segments(horizontal)
+    assert len(segments) == 1
+    dp = segments[0].DesignParameters
+    assert _label(dp.StartTag) == "P.O.B."
+    assert _label(dp.EndTag) == "P.O.E."
+
+
+def test_horizontal_tag_labels_and_adjacency():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    segments = _real_segments(horizontal)
+    assert len(segments) == 7
+
+    start_labels = [_label(s.DesignParameters.StartTag) for s in segments]
+    end_labels = [_label(s.DesignParameters.EndTag) for s in segments]
+
+    assert start_labels == ["P.O.B.", "P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T."]
+    assert end_labels == ["P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T.", "P.O.E."]
+
+    # every real segment has both tags set
+    assert all(s.DesignParameters.StartTag is not None for s in segments)
+    assert all(s.DesignParameters.EndTag is not None for s in segments)
+
+    # adjacent segments agree on the tag describing their shared transition point
+    for i in range(len(segments) - 1):
+        assert segments[i].DesignParameters.EndTag == segments[i + 1].DesignParameters.StartTag
+
+
+def test_vertical_tag_labels_and_adjacency():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    vertical = ifcopenshell.api.alignment.get_vertical_layout(alignment)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, vertical)
+
+    segments = _real_segments(vertical)
+    assert len(segments) == 9
+
+    start_labels = [_label(s.DesignParameters.StartTag) for s in segments]
+    end_labels = [_label(s.DesignParameters.EndTag) for s in segments]
+
+    assert start_labels == [
+        "V.P.O.B.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+    ]
+    assert end_labels == [
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "P.V.C.",
+        "P.V.T.",
+        "V.P.O.E.",
+    ]
+
+    assert all(s.DesignParameters.StartTag is not None for s in segments)
+    assert all(s.DesignParameters.EndTag is not None for s in segments)
+
+    for i in range(len(segments) - 1):
+        assert segments[i].DesignParameters.EndTag == segments[i + 1].DesignParameters.StartTag
+
+
+def test_cant_layout_boundary_tags():
+    file = _new_file_no_context()
+    alignment = ifcopenshell.api.alignment.create(file, "A1", include_cant=True, include_geometry=False)
+    cant = ifcopenshell.api.alignment.get_cant_layout(alignment)
+
+    dp1 = file.createIfcAlignmentCantSegment(
+        StartDistAlong=0.0,
+        HorizontalLength=100.0,
+        StartCantLeft=0.0,
+        EndCantLeft=0.0,
+        StartCantRight=0.0,
+        EndCantRight=0.0,
+        PredefinedType="CONSTANTCANT",
+    )
+    ifcopenshell.api.alignment.create_layout_segment(file, cant, dp1)
+
+    dp2 = file.createIfcAlignmentCantSegment(
+        StartDistAlong=100.0,
+        HorizontalLength=50.0,
+        StartCantLeft=0.0,
+        EndCantLeft=0.0,
+        StartCantRight=0.0,
+        EndCantRight=0.0,
+        PredefinedType="CONSTANTCANT",
+    )
+    ifcopenshell.api.alignment.create_layout_segment(file, cant, dp2)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, cant)
+
+    segments = _real_segments(cant)
+    assert _label(segments[0].DesignParameters.StartTag) == "C.P.O.B."
+    assert _label(segments[-1].DesignParameters.EndTag) == "C.P.O.E."
+    # CONSTANTCANT -> CONSTANTCANT is currently an unfilled "xx" placeholder in the cant lookup
+    # table (_get_segment_start_point_label.py) -- out of scope to fill in here.
+    assert _label(segments[0].DesignParameters.EndTag) == "xx"
+    assert _label(segments[-1].DesignParameters.StartTag) == "xx"
+
+
+def test_exact_tag_format():
+    file = _new_file()
+    alignment = _build_alignment(file)
+    horizontal = ifcopenshell.api.alignment.get_horizontal_layout(alignment)
+
+    ifcopenshell.api.alignment.update_alignment_parameter_segment_tags(file, horizontal)
+
+    start_station = ifcopenshell.api.alignment.get_alignment_start_station(file, alignment)
+    segments = _real_segments(horizontal)
+    assert segments[0].DesignParameters.StartTag == (
+        f"{ifcopenshell.util.alignment.station_as_string(file, start_station)} (P.O.B.)"
+    )
+
+
+test_wrong_layout_type_raises_type_error()
+test_not_nested_under_alignment_raises_value_error()
+test_returns_none()
+test_no_referents_or_rel_nests_created()
+test_no_real_segments_leaves_tags_none()
+test_single_real_segment_produces_only_boundary_tags()
+test_horizontal_tag_labels_and_adjacency()
+test_vertical_tag_labels_and_adjacency()
+test_cant_layout_boundary_tags()
+test_exact_tag_format()
diff --git a/src/ifcopenshell-python/test/api/alignment/test_update_key_point_referents.py b/src/ifcopenshell-python/test/api/alignment/test_update_key_point_referents.py
index d914763ddd..5e9984fb2e 100644
--- a/src/ifcopenshell-python/test/api/alignment/test_update_key_point_referents.py
+++ b/src/ifcopenshell-python/test/api/alignment/test_update_key_point_referents.py
@@ -66,6 +66,10 @@ def _pset_station(referent):
     return ifcopenshell.util.element.get_pset(referent, name="Pset_Stationing", prop="Station")
 
 
+def _label(name):
+    return name.rsplit("(", 1)[1].rstrip(")")
+
+
 def test_wrong_layout_type_raises_type_error():
     file = _new_file()
     alignment = _build_alignment(file)
@@ -181,7 +185,7 @@ def test_default_horizontal_labels_and_order():
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
 
     expected = ["P.O.B.", "P.C.", "P.T.", "P.C.", "P.T.", "P.C.", "P.T.", "P.O.E."]
-    assert [r.Name.split(" (")[0] for r in nest.RelatedObjects] == expected
+    assert [_label(r.Name) for r in nest.RelatedObjects] == expected
 
     stations = [_pset_station(r) for r in nest.RelatedObjects]
     assert stations == sorted(stations)
@@ -207,7 +211,7 @@ def test_default_vertical_labels_and_order():
         "P.V.T.",
         "V.P.O.E.",
     ]
-    assert [r.Name.split(" (")[0] for r in nest.RelatedObjects] == expected
+    assert [_label(r.Name) for r in nest.RelatedObjects] == expected
 
     segments = ifcopenshell.api.alignment.get_layout_segments(vertical)
     real_segments = segments[:-1] if ifcopenshell.api.alignment.has_zero_length_segment(vertical) else segments
@@ -224,7 +228,7 @@ def test_name_format():
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
     referent = nest.RelatedObjects[0]
     station = _pset_station(referent)
-    assert referent.Name == f"P.O.B. ({ifcopenshell.util.alignment.station_as_string(file, station)})"
+    assert referent.Name == f"{alignment.Name} {ifcopenshell.util.alignment.station_as_string(file, station)} (P.O.B.)"
 
 
 def test_geometric_placement_when_layout_has_representation():
@@ -292,7 +296,7 @@ def test_cant_layout_boundary_labels():
 
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, cant)
 
-    labels = [r.Name.split(" (")[0] for r in nest.RelatedObjects]
+    labels = [_label(r.Name) for r in nest.RelatedObjects]
     assert labels[0] == "C.P.O.B."
     assert labels[-1] == "C.P.O.E."
     # CONSTANTCANT -> CONSTANTCANT is currently an unfilled "xx" placeholder in the cant lookup
@@ -331,7 +335,7 @@ def test_single_real_segment_produces_only_boundary_labels():
     ifcopenshell.api.alignment.create_layout_segment(file, horizontal, design_parameters)
 
     nest = ifcopenshell.api.alignment.update_key_point_referents(file, horizontal)
-    labels = [r.Name.split(" (")[0] for r in nest.RelatedObjects]
+    labels = [_label(r.Name) for r in nest.RelatedObjects]
     assert labels == ["P.O.B.", "P.O.E."]