The XML FAQ

All white-space, including linebreaks (Mac CR, Win CR/LF, Unix LF), TAB characters, and normal spaces, even between ‘structural’ elements where no text can ever appear, is passed by the parser unchanged to the application (browser, formatter, viewer, converter, etc), identifying the context in which the white-space was found (element content, data content, or mixed content, if this information is available to the parser, eg from a DTD or Schema). This means it is the application's responsibility to decide what to do with such space, not the parser's:

• insignificant white-space between structural elements (space which occurs where only element content is allowed, ie between other elements, where text data never occurs) will get passed to the application (in SGML this white-space gets suppressed, which is why you can put all that extra space in HTML documents and not worry about it);

• significant white-space (space which occurs within elements which can contain text and markup mixed together, usually mixed content or PCDATA) will still get passed to the application exactly as under SGML. It is the application's responsibility to handle it correctly.

The parser must inform the application that white-space has occurred in element content, if it can detect it. (Users of SGML will recognize that this information is not in the ESIS, but it is in the Grove.)

 
<chapter> 
  <title> 
   My title for
   Chapter 1. 
  </title> 
    <para> 
text 
    </para> 
</chapter>
	  

In the example above, the application will receive all the pretty-printing linebreaks, TABs, and spaces between the elements as well as those embedded in the chapter title. It is the function of the application, not the parser, to decide which type of white-space to discard and which to retain. Many XML applications have configurable options to allow programmers or users to control how such white-space is handled.