Understanding XML Syntax

Last updated on by Digamber
XML syntax will be explored in this article. As far as XML syntax is concerned, we are merely referring to the rules that one must follow to write an XML application. First and forward, XML syntax is known for its straightforwardness. Therefore, you will find it easy to learn.

Let’s have a look at the main points one must keep in mind while writing XML code.

Well-formedness in XML Syntax

As per W3C standards, well-formedness is an important thing when it comes to an XML document. In order to have a well-formed XML document, a textual object must have:

  • It matches the production labeled document.
  • It adheres to the constraints provided by XML specification regarding well-formedness.

Each parsed entity is well-formed within the document, whether you reference them indirectly or directly.

We apologize if all this sound is confusing to you! Well, you must build the XML application correctly. That’s all you need to keep in mind!
XML Declaration

As far as XML declaration is concerned, it has to be the first item. We go for element to implement XML declaration.

Example:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

A Single Root Element Only

As far as XML documents are concerned, they are only supposed to have a single root element. You must contain all other elements under the root element. That’s the norm.

XML Markup

  • As far as XML documents are concerned, they constitute of data and XML markup.
  • Markup will have attributes and tags. Data is what you see between the tags or attributes.

Sample Food XML Markup

<?xml version="1.0" encoding="UTF-8"?>
<breakfast_menu>
   <food>
      <name>Belgian Waffles</name>
      <price>$5.95</price>
      <description>Two of our famous Belgian Waffles with plenty of real maple syrup</description>
      <calories>650</calories>
   </food>
   <food>
      <name>Strawberry Belgian Waffles</name>
      <price>$7.95</price>
      <description>Light Belgian waffles covered with strawberries and whipped cream</description>
      <calories>900</calories>
   </food>
   <food>
      <name>Berry-Berry Belgian Waffles</name>
      <price>$8.95</price>
      <description>Light Belgian waffles covered with an assortment of fresh berries and whipped cream</description>
      <calories>900</calories>
   </food>
   <food>
      <name>French Toast</name>
      <price>$4.50</price>
      <description>Thick slices made from our homemade sourdough bread</description>
      <calories>600</calories>
   </food>
   <food>
      <name>Homestyle Breakfast</name>
      <price>$6.95</price>
      <description>Two eggs, bacon or sausage, toast, and our ever-popular hash browns</description>
      <calories>950</calories>
   </food>
</breakfast_menu>

XML Declaration Example(Plant Catalog)

<?xml version="1.0" encoding="UTF-8"?>
<CATALOG>
   <PLANT>
      <COMMON>Bloodroot</COMMON>
      <BOTANICAL>Sanguinaria canadensis</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$2.44</PRICE>
      <AVAILABILITY>031599</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Columbine</COMMON>
      <BOTANICAL>Aquilegia canadensis</BOTANICAL>
      <ZONE>3</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$9.37</PRICE>
      <AVAILABILITY>030699</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Marsh Marigold</COMMON>
      <BOTANICAL>Caltha palustris</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Mostly Sunny</LIGHT>
      <PRICE>$6.81</PRICE>
      <AVAILABILITY>051799</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Cowslip</COMMON>
      <BOTANICAL>Caltha palustris</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$9.90</PRICE>
      <AVAILABILITY>030699</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Dutchman's-Breeches</COMMON>
      <BOTANICAL>Dicentra cucullaria</BOTANICAL>
      <ZONE>3</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$6.44</PRICE>
      <AVAILABILITY>012099</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Ginger, Wild</COMMON>
      <BOTANICAL>Asarum canadense</BOTANICAL>
      <ZONE>3</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$9.03</PRICE>
      <AVAILABILITY>041899</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Hepatica</COMMON>
      <BOTANICAL>Hepatica americana</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$4.45</PRICE>
      <AVAILABILITY>012699</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Liverleaf</COMMON>
      <BOTANICAL>Hepatica americana</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$3.99</PRICE>
      <AVAILABILITY>010299</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Jack-In-The-Pulpit</COMMON>
      <BOTANICAL>Arisaema triphyllum</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$3.23</PRICE>
      <AVAILABILITY>020199</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Mayapple</COMMON>
      <BOTANICAL>Podophyllum peltatum</BOTANICAL>
      <ZONE>3</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$2.98</PRICE>
      <AVAILABILITY>060599</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Phlox, Woodland</COMMON>
      <BOTANICAL>Phlox divaricata</BOTANICAL>
      <ZONE>3</ZONE>
      <LIGHT>Sun or Shade</LIGHT>
      <PRICE>$2.80</PRICE>
      <AVAILABILITY>012299</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Phlox, Blue</COMMON>
      <BOTANICAL>Phlox divaricata</BOTANICAL>
      <ZONE>3</ZONE>
      <LIGHT>Sun or Shade</LIGHT>
      <PRICE>$5.59</PRICE>
      <AVAILABILITY>021699</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Spring-Beauty</COMMON>
      <BOTANICAL>Claytonia Virginica</BOTANICAL>
      <ZONE>7</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$6.59</PRICE>
      <AVAILABILITY>020199</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Trillium</COMMON>
      <BOTANICAL>Trillium grandiflorum</BOTANICAL>
      <ZONE>5</ZONE>
      <LIGHT>Sun or Shade</LIGHT>
      <PRICE>$3.90</PRICE>
      <AVAILABILITY>042999</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Wake Robin</COMMON>
      <BOTANICAL>Trillium grandiflorum</BOTANICAL>
      <ZONE>5</ZONE>
      <LIGHT>Sun or Shade</LIGHT>
      <PRICE>$3.20</PRICE>
      <AVAILABILITY>022199</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Violet, Dog-Tooth</COMMON>
      <BOTANICAL>Erythronium americanum</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$9.04</PRICE>
      <AVAILABILITY>020199</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Trout Lily</COMMON>
      <BOTANICAL>Erythronium americanum</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$6.94</PRICE>
      <AVAILABILITY>032499</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Adder's-Tongue</COMMON>
      <BOTANICAL>Erythronium americanum</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$9.58</PRICE>
      <AVAILABILITY>041399</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Anemone</COMMON>
      <BOTANICAL>Anemone blanda</BOTANICAL>
      <ZONE>6</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$8.86</PRICE>
      <AVAILABILITY>122698</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Grecian Windflower</COMMON>
      <BOTANICAL>Anemone blanda</BOTANICAL>
      <ZONE>6</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$9.16</PRICE>
      <AVAILABILITY>071099</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Bee Balm</COMMON>
      <BOTANICAL>Monarda didyma</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$4.59</PRICE>
      <AVAILABILITY>050399</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Bergamot</COMMON>
      <BOTANICAL>Monarda didyma</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$7.16</PRICE>
      <AVAILABILITY>042799</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Black-Eyed Susan</COMMON>
      <BOTANICAL>Rudbeckia hirta</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Sunny</LIGHT>
      <PRICE>$9.80</PRICE>
      <AVAILABILITY>061899</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Buttercup</COMMON>
      <BOTANICAL>Ranunculus</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$2.57</PRICE>
      <AVAILABILITY>061099</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Crowfoot</COMMON>
      <BOTANICAL>Ranunculus</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$9.34</PRICE>
      <AVAILABILITY>040399</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Butterfly Weed</COMMON>
      <BOTANICAL>Asclepias tuberosa</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Sunny</LIGHT>
      <PRICE>$2.78</PRICE>
      <AVAILABILITY>063099</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Cinquefoil</COMMON>
      <BOTANICAL>Potentilla</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$7.06</PRICE>
      <AVAILABILITY>052599</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Primrose</COMMON>
      <BOTANICAL>Oenothera</BOTANICAL>
      <ZONE>3 - 5</ZONE>
      <LIGHT>Sunny</LIGHT>
      <PRICE>$6.56</PRICE>
      <AVAILABILITY>013099</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Gentian</COMMON>
      <BOTANICAL>Gentiana</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Sun or Shade</LIGHT>
      <PRICE>$7.81</PRICE>
      <AVAILABILITY>051899</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Blue Gentian</COMMON>
      <BOTANICAL>Gentiana</BOTANICAL>
      <ZONE>4</ZONE>
      <LIGHT>Sun or Shade</LIGHT>
      <PRICE>$8.56</PRICE>
      <AVAILABILITY>050299</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Jacob's Ladder</COMMON>
      <BOTANICAL>Polemonium caeruleum</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$9.26</PRICE>
      <AVAILABILITY>022199</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Greek Valerian</COMMON>
      <BOTANICAL>Polemonium caeruleum</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$4.36</PRICE>
      <AVAILABILITY>071499</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>California Poppy</COMMON>
      <BOTANICAL>Eschscholzia californica</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Sun</LIGHT>
      <PRICE>$7.89</PRICE>
      <AVAILABILITY>032799</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Shooting Star</COMMON>
      <BOTANICAL>Dodecatheon</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Mostly Shady</LIGHT>
      <PRICE>$8.60</PRICE>
      <AVAILABILITY>051399</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Snakeroot</COMMON>
      <BOTANICAL>Cimicifuga</BOTANICAL>
      <ZONE>Annual</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$5.63</PRICE>
      <AVAILABILITY>071199</AVAILABILITY>
   </PLANT>
   <PLANT>
      <COMMON>Cardinal Flower</COMMON>
      <BOTANICAL>Lobelia cardinalis</BOTANICAL>
      <ZONE>2</ZONE>
      <LIGHT>Shade</LIGHT>
      <PRICE>$3.02</PRICE>
      <AVAILABILITY>022299</AVAILABILITY>
   </PLANT>
</CATALOG>