爲什麼這個DTD無效？

Question

我試着用1-2驗證驗證這個DTD，但是我在爲什麼它是無效的不確定：

DTD代碼：

任何幫助將不勝感激！

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE cars 
[ 
    <!ELEMENT car (maker, model, year, colour, engine, number_of_doors, accessories)> 

    <!ELEMENT maker (#PCDATA)> 
    <!ELEMENT model (#PCDATA)> 
    <!ELEMENT year (#PCDATA)> 
    <!ELEMENT colour (#PCDATA)> 
    <!ELEMENT engine (number_of_cylinders)> 
    <!ELEMENT number_of_doors (#PCDATA)> 
    <!ELEMENT accessories (#PCDATA)> 

    <!ELEMENT number_of_cylinders (#PCDATA)> 

    <!ATTLIST accessories radio (yes|no) #REQUIRED 
     air_conditioning (yes|no) #REQUIRED 
     power_windows (yes|no) #REQUIRED 
     power_steering (yes|no) #REQUIRED 
     power_brakes (yes|no) #REQUIRED 
    > 
]> 

Answer 1

，從而與內部DTD子集XML文檔是有效的，做如下修改：

1. 更改文檔元素從cars到car。

2. 構建與給定內部子集關聯的XML。

   <?xml version="1.0" encoding="UTF-8"?> 
   <!DOCTYPE car 
   [ 
   <!ELEMENT car (maker, model, year, colour, engine, number_of_doors, accessories)> 
   
   <!ELEMENT maker (#PCDATA)> 
   <!ELEMENT model (#PCDATA)> 
   <!ELEMENT year (#PCDATA)> 
   <!ELEMENT colour (#PCDATA)> 
   <!ELEMENT engine (number_of_cylinders)> 
   <!ELEMENT number_of_doors (#PCDATA)> 
   <!ELEMENT accessories (#PCDATA)> 
   
   <!ELEMENT number_of_cylinders (#PCDATA)> 
   
   <!ATTLIST accessories radio (yes|no) #REQUIRED 
       air_conditioning (yes|no) #REQUIRED 
       power_windows (yes|no) #REQUIRED 
       power_steering (yes|no) #REQUIRED 
       power_brakes (yes|no) #REQUIRED> 
   ]> 
   <car> 
       <!-- Finish building out the XML per the internal subset. --> 
   </car> 
   

Answer 2

你可以用這個驗證是最適合DTD https://validator.w3.org/check