我收到一条错误消息“VC: Element Valid: Content model of element ‘recipes’;不允许使用元素“heading”在这个位置。”

Question

文件 C:\Users\Randy\Documents\XML\mealstxt.xml 无效。 元素“recipes”的内容模型不允许在此位置出现元素“heading”。 错误位置：食谱/标题 细节 VC：元素有效：元素“recipes”的内容模型不允许在此位置使用元素“heading”。

 <?xml version="1.0" encoding="UTF-8"?>
 <!--
    WebChef Recipes
Author: Randy White
date:   7/10/2011

Filename:         meals.xml
Supporting Files: meals.css

-->

<!DOCTYPE recipes
[
<!ELEMENT recipes (recipe,heading,heading2, heading3) >

<!ELEMENT heading (#PCDATA)>
<!ELEMENT heading2 (#PCDATA)>
<!ELEMENT heading3 (#PCDATA)>

<!ELEMENT ch_element (number, symbol, wgt)>
<!ATTLIST ch_element id ID #REQUIRED>

<!ELEMENT number (#PCDATA)>
<!ELEMENT symbol (#PCDATA)>
<!ELEMENT wgt (#PCDATA)>
]>

---

<?xml-stylesheet type="text/css" href="mealstxt.css" ?>

<recipes>
<heading>Chinese Recipes</heading>
<recipe>
  <name>Beggar's Chicken</name>
  <description>
     Beggar's chicken is a traditional dish from Hangzhoui. Legend has
     it that the disk was indeed created by beggars.
  </description>
  <ingredients>
     <ingredient>
        1 3lb fryer chicken
     </ingredient>
     <ingredient>
        2 teaspoons salt
     </ingredient>
     <ingredient>
        1 teaspoon ginger juice
     </ingredient>
     <ingredient>
        4 tablespoons oil
     </ingredient>
     <ingredient>
        1 chopped scallion
     </ingredient>
     <ingredient>
        4 ounces shredded pork
     </ingredient>
     <ingredient>
        1 tablespoon sherry
     </ingredient>
     <ingredient>
        1 tablespoon light soy sauce
     </ingredient>
     <ingredient>
        1 teaspoon sugar
     </ingredient>
     <ingredient>
        2 ounces preserved Yuanne cabbage, julienne
     </ingredient>
     <ingredient>
        aluminum foil
     </ingredient>
  </ingredients>
  <instructions>
     <step>Rub cleaned chicked with salt. Rub ginger juice inside of chicken.
           Set aside.
     </step>
     <step>Heat 2 tablespoons of oil in wok. Stir-fry scallion. Add pork. 
           Stir on high heat. Add sherry, sauce, and sugar. Remove to bowl.
     </step>
     <step>Heat 2 tablespoons of oil in wok. Stir-fry cabbage. Pour in
           meat mixture. Stir-fry one minute.
     </step>
     <step>Stuff meat mixture into chicken. Wrap in aluminum foil and place
           in pan.
     </step>
     <step>Back chicken 1 hr at 350 degrees. Turn up heat to 400 degrees
           and bake 15 more minutes.
     </step>
     <step>Remove foil. Remove stuffing from chicken to platter. Cut 
           chicken into bit-sized pieces. Arrange on top of stuffing.
     </step>
  </instructions>
  </recipe>
  <recipe>
  <name>Chicken with Chestnuts</name>
  <description>
     A popular dish from Shanghai, this dish is quick and easy to make.
  </description>
  <ingredients>
     <ingredient>
        1 pound chestnuts
     </ingredient>
     <ingredient>
        4 tablespoons oil
     </ingredient>
     <ingredient>
        1 slice ginger, 1/8" thick
     </ingredient>
     <ingredient>
        1 scallion, cut into four pieces
     </ingredient>
     <ingredient>
        1 3lb fryer, cut into 2" pieces
     </ingredient>
     <ingredient>
        2 tablespoons sherry
     </ingredient>
     <ingredient>
        1/2 teaspoon salt
     </ingredient>
     <ingredient>
        1/4 cup dark soy sauce
     </ingredient>
     <ingredient>
        2 cups water
     </ingredient>
     <ingredient>
        1 tablespoon sugar
     </ingredient>
   </ingredients>
   <instructions>
     <step>Cut chestnuts into halves. Cover with water. Simmer 30 minutes.
           Remove shells and skin. Set aside.
     </step>
     <step>Heat oil in wok. Stir-fry ginger and scallions 30 seconds. Add
           chicken. Stir-fry 1 minute. Add sherry, salt, soy sauce, and
           water. Cover and simmer 30 minutes.
     </step>
     <step>Add chestnuts and sugar. Simmer 10 minutes more.
     </step>
     <step>Bring to high heat and cook 5 minutes. Remove to platter. 
           Serve hot.
     </step>
  </instructions>
  </recipe>
  <recipe>
  <name>Salted Duck</name>
  <description>
     This dish from Nanking is served cold. It works best on a buffet table.
  </description>
  <ingredients>
     <ingredient>
        1 5-lb duck
     </ingredient>
     <ingredient>
        2 tablespoons salt
     </ingredient>
     <ingredient>
        1 tablespoon ginger juice
     </ingredient>
     <ingredient>
        Water
     </ingredient>
  </ingredients>
  <instructions>
     <step>Wash and clean duck. Wipe dry.
     </step>
     <step>Rub duck with salt inside and out. Wrap in foil. Refrigerate
           3 days.
     </step>
     <step>Rub inside of duck with ginger juice.
     </step>
     <step>Put duck in large saucepan. Cover with water. Bring to boil.
           Simmer 2 hours.
     </step>
     <step>Chill. Chop into bite-sized pieces and serve cold.
     </step>
  </instructions>
 </recipe>
 <recipe>
  <name>Beef with Onions</name>
  <description>
     A quick and easy dish from Shanghai. Best served on a bed of rice.
  </description>
  <ingredients>
     <ingredient>
        1 lb beef steak, julienne
     </ingredient>
     <ingredient>
        1 teaspoon salt
     </ingredient>
     <ingredient>
        3 egg white
     </ingredient>
     <ingredient>
        3 tablespoons cornstarch
     </ingredient>
     <ingredient>
        4 cups oil for deep-frying
     </ingredient>
     <ingredient>
        4 sliced onions
     </ingredient>
     <ingredient>
        1 tablespoon dry sherry
     </ingredient>
     <ingredient>
        1 tablespoon sugar
     </ingredient>
     <ingredient>
        4 tablespoons dark soy sauce
     </ingredient>
   </ingredients>
   <instructions>
     <step>Combine beef, salt, egg white and cornstarch. Mix well.
     </step>
     <step>Heat oil in wok. Deep-fry beef until seared. Drain.
     </step>
     <step>Reheat 2 tablespoons of oil in wok. Add onions. Stir-fry
           until soft and browned.
     </step>
     <step>Add beef, sherry, sugar, and soy sauce. Stir-fry 1 minute
           until beef is glazed and brown.
     </step>
   </instructions>
   </recipe>
   <recipe>
   <name>Szechwan Beef</name>
   <description>
     One of the classic chinese dishes.
   </description>
   <ingredients>
     <ingredient>
        1 lb flank steak, shredded
     </ingredient>
     <ingredient>
        1 teaspoon salt
     </ingredient>
     <ingredient>
        2 egg white
     </ingredient>
     <ingredient>
        2 tablespoons cornstarch
     </ingredient>
     <ingredient>
        4 cups oil for deep-frying
     </ingredient>
     <ingredient>
        1/2 cup shredded bamboo shoots.
     </ingredient>
     <ingredient>
        1/2 cup shredded green pepper
     </ingredient>
     <ingredient>
        1 tablespoon dark soy sauce
     </ingredient>
     <ingredient>
        1 teaspoon chili paste with garlic
     </ingredient>
     <ingredient>
        1/2 ounce mung bean
     </ingredient>
    </ingredients>
    <instructions>
     <step>Mix beef, salt, egg white, and cornstarch.
     </step>
     <step>Heat oil in wok. Deep-fry beef 1 minute. Drain. Remove.
     </step>
     <step>Reheat 2 tablespoons of oil in wok. Stir-fry bamboo shoots
           and green pepper 30 seconds. Add beef, soy sauce, chili paste
           with garlic, and sugar. Stir-fy 1 minute. Remove.
     </step>
     <step>Reheat 2 cups of oil in wok to smoking hot. Deep-fry mung bean
           1 second. Remove to platter. Pour meat over fried
           mung bean.
     </step>
     </instructions>
     </recipe>
     <recipe>
     <name>Twice-cooked Pork</name>
     <description>
     This Szechwan dish is extremely popular.
     </description>
     <ingredients>
     <ingredient>
        1 lb pork loin
     </ingredient>
     <ingredient>
        2 cups water
     </ingredient>
     <ingredient>
        5 tablespoons oil
     </ingredient>
     <ingredient>
        1 leek, cut into 1" pieces
     </ingredient>
     <ingredient>
        1/2 red pepper, cut into thin strips
     </ingredient>
     <ingredient>
        1/2 green pepper, cut into thin strips
     </ingredient>
     <ingredient>
        1 tablespoon bean sauce
     </ingredient>
     <ingredient>
        1 teaspoon ginger
     </ingredient>
     <ingredient>
        1 tablespoon sherry
     </ingredient>
     <ingredient>
        1 tablespoon dark soy sauce
     </ingredient>
     <ingredient>
        1 tablespoon chili paste with garlic
     </ingredient>
     <ingredient>
        2 gloves minced garlic
     </ingredient>
     <ingredient>
        1 thin slice minced ginger
     </ingredient>
     <ingredient>
        2 scallion, cut into 1" pieces
     </ingredient>
    </ingredients>
    <instructions>
     <step>Cook pork in water 20 minutes. Drain and cool.
     </step>
     <step>Cut pork across grains into paper-thin slices.
     </step>
     <step>Heat 2 tablesppons of oil in wok. Stir-fry leek until wilted.
           Add red and green peppers. Stir-fry 30 seconds. Remove.
     </step>
     <step>Heat 2 more tablespoons of oil in wok. Add pork. Stir-fry
           1 minute. Remove.
     </step>
     <step>Heat 1 tablespoon oil in wok. Stir-fry bean sauce under
           moderate heat. Add sugar. Stir-fry 1 minute. Add pork, leek,
           and peppers. Cook over high heat for 1 minute. Add sherry, 
           soy sauce, and chili paste with garlic. Add garlic and
           ginger. Stir-fry thoroughly. Add scallion. Stir fry for 
           another 30 seconds.
     </step>
    </instructions>
    </recipe>
    </recipes>

Answer 1

DTD 指定根 元素允许的内容：

<!ELEMENT recipes (recipe,heading,heading2, heading3) >

这些内容按顺序，即 元素（以及您的 DTD 只允许一个 - 您可能希望 recipe* 允许多个元素）必须位于 元素之前。

这可能更有意义：

<!ELEMENT recipes (heading, heading2, heading3, recipe*) >