XML DTD "Content of element type must match "空"

Question

第一次使用 DTD。我看过一些例子，但我不太确定哪里出错了。当我验证我的 XML 时，不断出现的错误是

The content of element type "stanza" must match 'null'.

这是我的 XML 和我的 DTD 的一部分：

<!DOCTYPE Week4 [
<!ELEMENT Week4 (poems,videos)>
<!ELEMENT poems (poem1,poem2,poem3,poem4)>
<!ELEMENT poem1 (#PCDATA)>
<!ELEMENT author (#PCDATA)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT stanza (#PCDATA)>
<!ELEMENT line (#PCDATA)>
]>
<Week4>
<poems>
    <poem1>
    <author>Edwin Arlington Robinson</author>
    <title>Richard Cory</title>
    <stanza>
        <line>Whenever Richard Cory went down town,</line>
        <line>We people on the pavement looked at him:</line>
        <line>He was a gentleman from sole to crown,</line>
        <line>Clean favored, and imperially slim.</line>
    </stanza>

Answer 1

改变

<!ELEMENT stanza (#PCDATA)>

到

<!ELEMENT stanza (line*)>

允许 stanza 由零个或多个 line 元素组成。

XML DTD "Content of element type must match "空"

XML DTD "Content of element type must match "null"

xml

dtd

xml-validation