I use a fantastic javascript organization tree generator named \"ECOTree\" but the drawing does not work when I put . Labels in the boxes a
It tells the version i.e the page is written in HTML5. Basically it is the instruction to the web browser about what version of HTML the page is written in and even tell web browser how to render the page.
Following are list of HTML Doctype Declarations List:
http://www.w3.org/QA/2002/04/valid-dtd-list.html