<?xml version = "1.0" encoding ="utf-8" ?>
 <!ELEMENT shopping_cart (item*, deal*) >
 <!ATTLIST shopping_cart userID CDATA #REQUIRED >
    <!ELEMENT deal (item+) >
    <!ELEMENT item (ID, type, price, vendor) >
      <!ELEMENT ID (#PCDATA)>
      <!ELEMENT type (#PCDATA)>
      <!ELEMENT price (#PCDATA)>
      <!ELEMENT vendor (#PCDATA)>
 

 <?xml version="1.0" encoding="UTF-8" ?>

 <!DOCTYPE Company [
 <!ELEMENT Company (shopping_cart) >
 <!ELEMENT shopping_cart (item+) >
 <!ELEMENT item (ID,type,price,vendor) >
 <!ELEMENT ID (#PCDATA)>
 <!ELEMENT type (#PCDATA)>
 <!ELEMENT price (#PCDATA)>
 <!ELEMENT vendor (#PCDATA)>
 <!ATTLIST shopping_cart user CDATA #REQUIRED>
 <!ENTITY vendor "Sunshine Farm">

  <shopping_cart user="sida">
      <item>
          <ID>1</ID>
          <type>orange</type>
          <price>$1.oo</price>
          <vendor>&vendor;</vendor>
      </item>
      <item>
          <ID>2</ID>
          <type>apple</type>
          <price>$2.oo</price>
          <vendor>&vendor;</vendor>
      </item>
  </shopping_cart>

 <?xml version = "1.0" encoding ="utf-8" ?>
 <!-- shopping_cart.dtd  -->
 <!ELEMENT shopping_cart (items*, user)>
 <!ELEMENT item (id, type, price, vendor)>
 <!ELEMENT user (#PCDATA)>
 <!ELEMENT id (#PCDATA)> 
 <!ELEMENT type (#PCDATA)>
 <!ELEMENT price (#PCDATA)>
 <!ATTLIST price currency #CDATA #IMPLIED> 
 <!ELEMENT vendor (#PCDATA)> 
 <!ENTITY ess_deal "bread and eggs">
 <!ENTITY meat_deal "ham and beef">

 <?xml version = "1.0" encoding ="utf-8" ?>
 <!-- shopping_cart.dtd -->
 
 <!ELEMENT cart (item*) >
 <!ELEMENT item (ID, type, price, vendor) >
 <!ELEMENT ID (#PCDATA)>
 <!ELEMENT type (#PCDATA)>
 <!ELEMENT price (#PCDATA)>
 <!ELEMENT vendor (#PCDATA)>
 <!ENTITY electronics-vendor "Apple">
 <!ATTLIST type perishable (yes|no) #IMPLIED >
 <!ATTLIST type category (Grocery|Electronics|Clothing) #REQUIRED >
 <!ATTLIST cart user CDATA #REQUIRED>
 <!ENTITY apple_deal "iPad Pro + Apple Pencil 2 + Paper-like Screen Protector">

 <!-- shopping_cart.xml -->
 <?xml version="1.0" encoding="UTF-8"?>
 <?xml-model href="shopping_cart.dtd" type="application/xml-dtd"?>
 
 <cart user="Niraj">
    <item>
        <ID>1</ID>
        <type category="Electronics">Smart Phone</type>
        <price>$900.00</price>
        <vendor>&electronics-vendor;</vendor>
    </item>
    
    <item>
        <ID>2</ID>
        <type category="Clothing">T-shirt</type>
        <price>$30.00</price>
        <vendor>Peter England</vendor>
    </item>
    <item>
        <ID>3</ID>
        <type perishable="yes" category="Grocery">Fruit</type>
        <price>$2.00</price>
        <vendor>D-Mart</vendor>
    </item>
    <item>
        <ID>4</ID>
        <type category="Electronics">&apple_deal;</type>
        <price>$1100.00</price>
        <vendor>&electronics-vendor;</vendor>
    </item>
 </cart>

 <?xml version = "1.0" encoding ="utf-8" ?>
 <!-- shopping_cart.dtd -->
 <!ELEMENT user_cart (cart_items*)>
 <!ATTLIST user_cart user_name #CDATA >
 <!ELEMENT cart_items (id, price, vendor, model?)>
 <!ELEMENT id (#PCDATA) >
 <!ELEMENT price (#PCDATA) >
 <!ELEMENT vendor (#PCDATA) >
 <!ELEMENT model (#PCDATA) >
 <!ENTITY gadgetsCombo "populated_laptop_element, populated_speakers_element, populated_monitor_element" >

 <?xml version = "1.0" encoding = "utf-8" ?>
 <!ELEMENT cart (user, item*) >
 <!ELEMENT user (#PCDATA)>
 <!ELEMENT item (id, type, price, vendor) >
 <!ELEMENT id (#PCDATA) >
 <!ELEMENT type (#PCDATA) >
 <!ELEMENT price (#PCDATA) >
 <!ELEMENT vendor (#PCDATA) >
 <!ATTLIST vendor license CDATA #REQUIRED>
 <!ENTITY deal "item1,item2,item3">

 <?xml version = "1.0" encoding ="utf-8" ?>
 <!-- shopping_cart.dtd -->
 <!ELEMENT shopping_cart (item*) >
 <!ATTLIST shopping_cart user CDATA #REQUIRED >
 <!ELEMENT item (ID, type, price, vendor) >
 <!ELEMENT ID (#PCDATA) >
 <!ELEMENT type (#PCDATA) >
 <!ELEMENT price (#PCDATA) >
 <!ELEMENT vendor (#PCDATA) >
 <!ENTITY asale “anniversary_sale”>

	<?xml version = "1.0" encoding ="utf-8" ?>
	<!-- shopping_cart.dtd  -->
	<!ELEMENT user (shopping_cart)
	<!ELEMENT shopping_cart (item*)>
	<!ELEMENT item (id, type, price, vendor)>
	<!ELEMENT id>
	<!ELEMENT type>
	<!ELEMENT price>
	<!ELEMENT vendor>
	<!ATTLIST price currency CDATA #REQUIRED
			locations CDATA #IMPLIED>
	<!ENTITY soccer_kit_deal "<item><id>cones</id><type>sports</type><price>10.00</price><vendor>Company1</vendor></item>,<item><id>ball</id><type>sports</type><price>5.50</price><vendor>Company2</vendor></item>,<item><id>gloves</id><type>sports</type><price>15.00</price><vendor>Company3</vendor></item>,<item><id>cleats</id><type>sports</type><price>35.00</price><vendor>Company3</vendor></item>">