Déclaration de balisage DTD externe attendue [duplicate]

Question

J'ai un problème avec la validation XML lorsque j'ajoute une validation DTD externe. Cela fonctionne normalement:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE booklist [
<!ELEMENT booklist (book)*>
<!ELEMENT book (author,title,published?)>
<!ELEMENT author (firstname,lastname)>
<!ELEMENT firstname (#PCDATA)>
<!ELEMENT lastname (#PCDATA)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT published (#PCDATA)>
<!ATTLIST book genre (Science|Fiction) #REQUIRED>
<!ATTLIST book format (Paperback|Hardcover) "Paperback">
]>
<booklist>
  <book genre="Fiction" format="Paperback">
    <author>
      <firstname>Name</firstname>
      <lastname>Surname</lastname>
    </author>
    <title>Sample</title>
    <published>2020</published>
  </book>
</booklist>

Lorsque j'essaie d'ajouter une déclaration DTD externe, l'éditeur de copie XML génère une erreur

Erreur fatale à la ligne 1, colonne 3: déclaration de balisage attendue

XML

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE booklist SYSTEM "booklist.dtd">
<booklist>
  <book genre="Fiction" format="Paperback">
    <author>
      <firstname>Name</firstname>
      <lastname>Surname</lastname>
    </author>
    <title>Sample</title>
    <published>2020</published>
  </book>
</booklist>

DTD

<!DOCTYPE booklist [
<!ELEMENT booklist (book)*>
<!ELEMENT book (author,title,published?)>
<!ELEMENT author (firstname,lastname)>
<!ELEMENT firstname (#PCDATA)>
<!ELEMENT lastname (#PCDATA)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT published (#PCDATA)>
<!ATTLIST book genre (Science|Fiction) #REQUIRED>
<!ATTLIST book format (Paperback|Hardcover) "Paperback">
]>

Qu'est-ce que je fais mal ?

Answer 1

Supprimez le DOCTYPEwrapper de votre sous-ensemble externe:

DTD externe

<!ELEMENT booklist (book)*>
<!ELEMENT book (author,title,published?)>
<!ELEMENT author (firstname,lastname)>
<!ELEMENT firstname (#PCDATA)>
<!ELEMENT lastname (#PCDATA)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT published (#PCDATA)>
<!ATTLIST book genre (Science|Fiction) #REQUIRED>
<!ATTLIST book format (Paperback|Hardcover) "Paperback">