In sloppy HTML, the following would be fine: However, XHTML dictates we write it like this: Notice, I lowered all the attribute names, quoted all the attribute values and added the space, ...
The free and fully-featured Markdown editor for Windows allows you to write using an easy-to-read, easy-to-write plain text format, and then convert it to structurally valid XHTML (or HTML). In short, ...