The XML FAQ: What are these terms DTDless, valid, and well-formed?
Well formed in relation to XML means that it has no syntax, spelling, For example, a parser would be needed to compare an XML document to a DTD. is a difference between a valid XML document and a well-formed one. to be valid if it is associated with a document type definition(DTD). Here's how to convert a basic XML document into something that is Well-Formed and valid so that your XML works where it's supposed to work.
Other key syntax rules provided in the specification include: It contains only properly encoded legal Unicode characters. The begin, end, and empty-element tags that delimit the elements are correctly nested, with none missing and none overlapping.
Well-formed document - Wikipedia
The element tags are case-sensitive; the beginning and end tags must match exactly. Tag names cannot contain any of the characters!
There is a single "root" element that contains all the other elements. You don't need to describe or explain what these tags mean. If all tags in a document are correctly formed and follow XML guidelines, then a document is considered as well formed. This policy, occasionally referred to as draconian stands in notable contrast to the behavior of programs that process HTMLwhich are designed to produce a reasonable result even in the presence of severe markup errors  in the spirit of Postel's law "Be conservative in what you send; be liberal in what you accept".
XML - Validation
It helps to clarify XML beyond the typical sense of it. For example, while most XML Document Type Definitions utilize left and right angle brackets as content delimiters, strictly speaking this is not a necessity though a delimiter should be terse and concise.
- What is the difference between well-formed and valid XML document?
- Well-formed vs Valid XML
- What is the difference between well formed and valid XML documents?
The left and right angle bracket codes are a convention, albeit clear and distinctive, not an absolute requirement. The concept of well-formed document also allows for the comprehension of the abstract nature of XML.
Citing a title of a book? A second, closely related reason, is that editors of digital texts have to design their work to function with any kind of automated processing — not just one program used to generate a print edition or series of web pages. Scholarly editions are time-consuming to produce, and the number of scholarly editors is too small to justify redoing an edition.
Digital editions must therefore specify the semantics of a text explicitly and unambiguously: A third reason to prefer explicitly indicating the semantics of a text is that, as we shall see momentarily, the technologies for textual markup work with simple text formats that integrate easily with other essential functions we shall consider later in this seminar specifically, version control systems to manage multiple versions of a single text, and build systems to manage collections of multiple texts.
Textual markup uses the same characters that are used for the text, but follows rules that allow us or our software to distinguish between text content and markup. In XML, pointed brackets enclose markup: Here are a few lines from the top of the web page at http: Your browser will normally use the markup information to decide to place the title text in the title bar of your window, rather than in the main content area.
In laying out the page for you to read, your browser will normally draw that heading text more prominently than other text on the page. The contents of an XML document fall into the following distinct categories, which an XML editor like oXygen or JEdit will typically display in easily distinguished forms e.
What is the difference between well formed and val - salonjardin.info
Elements Elements are the heart of an XML document. In XML, every element has an explicit beginning and ending. Syntactically, the beginning of the element is given by the name contained within angle brackets.