Give the CommonMark blocks a directive form for what their spelling cannot hold

src/directive-attributes.ts

@@ -11,10 +11,14 @@ export function isBareToken(text: string): boolean {
   return bareToken.test(text)
 }
 
-export function vocabularyPairs(attrs: AdfAttributes, vocabulary: AttributeVocabulary, slot: string | undefined): [string, string][] | undefined {
+export function vocabularyPairs(
+  attrs: AdfAttributes,
+  vocabulary: AttributeVocabulary,
+  spelledElsewhere: readonly (string | undefined)[],
+): [string, string][] | undefined {
   const pairs: [string, string][] = []
   for (const [key, value] of Object.entries(attrs)) {
-    if (key === slot) continue
+    if (spelledElsewhere.includes(key)) continue
     const kind = Object.hasOwn(vocabulary, key) ? vocabulary[key] : undefined
     if (kind === undefined) return undefined
     const spelled = spellAttributeValue(value, kind)