diff --git a/CHANGELOG.md b/CHANGELOG.md
index 03ef401..29a40eb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,8 @@ Second pre-release. Continues the W3C XSTS schema-validity campaign: **invalid-s
 
 ### Fixed
 
+- XSTS invalid-schemas-accepted (#145): an `xsd:notation` declaration is held to its `(annotation?)` content model. A notation may carry only an optional `annotation` child, so any other element child, or any non-whitespace character content, is now rejected (`notatG`). Caught three invalid schemas: invalid-schemas-accepted 214 → 211, no other bucket moved.
+
 - XSTS invalid-schemas-accepted (#145): a `list` simple type must draw its item type from exactly one of an `itemType` attribute or an inline `simpleType` child (neither, or both, is invalid), and a `union` must declare at least one member type through a `memberTypes` attribute or an inline `simpleType` child (an empty `union` declares none), per `src-simple-type.2`/`.3`. Caught one invalid schema: invalid-schemas-accepted 215 → 214, no other bucket moved.
 
 - XSTS invalid-schemas-accepted (#145): a simple type without its own `final` attribute now inherits the schema's `finalDefault` as its `{final}` property (XSD 1.0 Schemas §3.14.2), so `finalDefault="list"` or `"union"` blocks the matching list-item or union-member derivation just as an explicit `final` would. An explicit `final=""` still overrides the default back to no restriction. Caught two invalid schemas: invalid-schemas-accepted 217 → 215, no other bucket moved.
diff --git a/Sources/Schema/SchemaNotationValidity.swift b/Sources/Schema/SchemaNotationValidity.swift
index 5032165..419134e 100644
--- a/Sources/Schema/SchemaNotationValidity.swift
+++ b/Sources/Schema/SchemaNotationValidity.swift
@@ -21,6 +21,9 @@ extension PureXML.Schema.XSDParser {
                 if PureXML.Schema.XSDNode.attribute(child, "public") == nil, PureXML.Schema.XSDNode.attribute(child, "system") == nil {
                     errors.append("notation '\(name)' must specify at least one of public or system attributes")
                 }
+                if notationHasForbiddenContent(child) {
+                    errors.append("notation '\(name)' may contain only an optional annotation, no other element or character content")
+                }
                 let qName = PureXML.Model.QualifiedName(localName: name, namespaceURI: containerNamespace)
                 declaredNotations.insert(qName)
             }
@@ -35,6 +38,20 @@ extension PureXML.Schema.XSDParser {
         return errors
     }
 
+    /// Whether a `notation` declaration carries content its `(annotation?)` model
+    /// forbids: any element child other than an `xsd:annotation`, or any
+    /// non-whitespace character content. Whitespace and a single optional
+    /// annotation are allowed.
+    private static func notationHasForbiddenContent(_ node: XSDTree) -> Bool {
+        let hasForeignElement = PureXML.Schema.XSDNode.elementChildren(node).contains {
+            $0.name?.namespaceURI != xsdNamespace || PureXML.Schema.XSDNode.localName($0) != "annotation"
+        }
+        let hasText = node.children.contains {
+            ($0.kind == .text || $0.kind == .cdata) && $0.value.contains { !$0.isWhitespace }
+        }
+        return hasForeignElement || hasText
+    }
+
     private static func walkSimpleTypes(
         _ node: XSDTree,
         context: PureXML.Schema.XSDContext,
diff --git a/Tests/XSTSSuiteTests.swift b/Tests/XSTSSuiteTests.swift
index 6cc4897..962fcfb 100644
--- a/Tests/XSTSSuiteTests.swift
+++ b/Tests/XSTSSuiteTests.swift
@@ -105,8 +105,12 @@ struct XSTSSuiteTests {
     /// `memberTypes` or an inline simpleType child (src-simple-type.2/.3), then
     /// caught one more invalid schema: invalid-schemas accepted 215 → 214, no other
     /// bucket moved.
+    /// Enforcing the `(annotation?)` content model of an `xsd:notation` declaration
+    /// (no element child other than an annotation, no non-whitespace character
+    /// content) then caught three more invalid schemas: invalid-schemas accepted
+    /// 214 → 211, no other bucket moved.
     private let knownSchemaValidRejected = 1
-    private let knownSchemaInvalidAccepted = 214
+    private let knownSchemaInvalidAccepted = 211
     private let knownInstanceValidRejected = 3
     private let knownInstanceInvalidAccepted = 132