why and not ?

Question

This is one of those things that you read once, say "aha!" and then forget. Exactly my case.

Why is the line-break tag in xhtml preferentially written with a space <br /> and not in the also ok format <br/> ? I remember the reason was interesting, and as you can imagine it's not easy to find with google.

For sure it's not an issue of xml well-formedness. From W3C

[44]    EmptyElemTag       ::=      '<' Name (S Attribute)* S? '/>' 

   Empty-element tags may be used for any element which has no content, whether
   or not it is declared using the keyword EMPTY. For interoperability, the 
   empty-element tag should be used, and should only be used, for elements which 
   are declared EMPTY.

Examples of empty elements:

<IMG align="left"  src="http://www.w3.org/Icons/WWW/w3c_home" /> 
<br></br> 
<br/>

So the space at the end is optional.

Answer 1

Both are correct.