Add explanation for design of schema type record

michaelhkay · Nov 10, 2024 · 907bfa2 · 907bfa2
1 parent c221067
commit 907bfa2
Showing 1 changed file with 11 additions and 0 deletions.
diff --git a/specifications/xpath-functions-40/src/xpath-functions.xml b/specifications/xpath-functions-40/src/xpath-functions.xml
@@ -7964,6 +7964,17 @@ return <table>
 
             <?record-description schema-type-record?>
 
+         <note>
+            <p>Simple properties of a schema type that can be expressed as strings or booleans are
+            represented in this record structure directly as atomic field values, while complex properties
+            whose values are themselves types (for example, <code>base-type</code> and <code>primitive-type</code>)
+            are represented as functions. This is done partly to make it easier for implementations to compute
+            complex properties on demand rather than in advance, and partly to ensure that the overall
+            structure is always acyclic. For example, the primitive type of <code>xs:decimal</code> is itself
+            <code>xs:decimal</code>, and if this were represented as a field value without a guarding function,
+            serialization of the map using the JSON output method would not terminate.</p>
+         </note>
+
          <div2 id="functions-returning-type-information">
             <head>Functions returning type information</head>