From a54b21b838edd49636634e78ee44eb6430db86a7 Mon Sep 17 00:00:00 2001
From: Richard Brice <37087370+RickBrice@users.noreply.github.com>
Date: Thu, 5 Feb 2026 04:37:58 -0800
Subject: [PATCH] Fixes documentation and adds test for expected type

---
 .../api/alignment/_create_offset_curve_representation.py   | 7 ++++++-
 .../ifcopenshell/api/alignment/create_as_offset_curve.py   | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/src/ifcopenshell-python/ifcopenshell/api/alignment/_create_offset_curve_representation.py b/src/ifcopenshell-python/ifcopenshell/api/alignment/_create_offset_curve_representation.py
index 6850013c96..bb3fa6cbe8 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/alignment/_create_offset_curve_representation.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/alignment/_create_offset_curve_representation.py
@@ -28,7 +28,7 @@ def _create_offset_curve_representation(
     file: ifcopenshell.file, alignment: entity_instance, offsets: Sequence[entity_instance]
 ) -> None:
     """
-    Create geometric representation for the alignment based on an IfcPolyline
+    Create geometric representation for the alignment based on an IfcOffsetByDistances curve
 
     :param alignment: The alignment for which the representation is being created
     :return: None
@@ -36,6 +36,11 @@ def _create_offset_curve_representation(
     expected_type = "IfcAlignment"
     if not alignment.is_a(expected_type):
         raise TypeError(f"Expected {expected_type} but got {alignment.is_a()}")
+    
+    expected_type = "IfcPointByDistaceExpression"
+    for offset in offsets:
+        if not offset.is_a(expected_type):
+            raise TypeError(f"Expected {expected_type} but got {offset.is_a()}")
 
     axis_geom_subcontext = ifcopenshell.api.alignment.get_axis_subcontext(file)
 
diff --git a/src/ifcopenshell-python/ifcopenshell/api/alignment/create_as_offset_curve.py b/src/ifcopenshell-python/ifcopenshell/api/alignment/create_as_offset_curve.py
index b24fb16b29..6ac56af362 100644
--- a/src/ifcopenshell-python/ifcopenshell/api/alignment/create_as_offset_curve.py
+++ b/src/ifcopenshell-python/ifcopenshell/api/alignment/create_as_offset_curve.py
@@ -39,7 +39,7 @@ def create_as_offset_curve(
 
     :param file:
     :param name: name assigned to IfcAlignment.Name
-    :param offsets: offsets from the basis curve that defines the offset curve, expected to be IfcOffsetCurveByDistances.
+    :param offsets: offsets from the basis curve that defines the offset curve, expected to be IfcPointByDistanceExpression.
     :param start_station: station value at the start of the alignment
     :return: Returns an IfcAlignment
     """