diff --git a/VariantShredding.md b/VariantShredding.md
index bbebbddb..4f7d6142 100644
--- a/VariantShredding.md
+++ b/VariantShredding.md
@@ -303,6 +303,9 @@ def construct_variant(metadata: Metadata, value: Variant, typed_value: Any) -> V
                 assert typed_value.keys().isdisjoint(value.keys()), "object keys must be disjoint"
 
                 # union the shredded fields and non-shredded fields
+                # (field IDs and offsets must be in the order of the
+                # corresponding field names, sorted lexicographically
+                # (unsigned byte ordering for UTF-8))
                 return VariantObject(metadata, object_fields).union(VariantObject(metadata, value))
 
             else: