With Netscape 6 the next move toward standards-based browsing is here. True, it will be a gradual move. And who knows what the boys in Redmond will do with MSIE -- they have had a track record of turning the browser into a weapon of war.
However, I've decided the smartest thing is to make at least all our company's new work compliant. Then we'll patch up our old stuff as needed.
So, trying to list the types of things that need attention, I came up with this:
IE5/Mac and NS6 try to comply with standards for pages using certain DOCTYPE declarations. They use a backward-compatible mode for other pages by attempting to guess the meaning and construct a valid tree for the Gecko and Tasman rendering engines. I suppose IE6 will be using the Tasman engine and the same compatibility mode logic.
As I recall, any XHTML 1.0 DOCTYPE triggers standard mode, as will HTML 4.0 Strict. HTML 4.0 Transitional does with NS6, but only if you use a full DOCTYPE with the DTD URL. DOCTYPEs for HTML prior to 4.0 are rendered in Quirks mode. I think IE5/Mac renders 4.0 Transitional in standard mode in all cases, but I'm not sure about that.
Passing validations increases the odds not just of working correctly in new browsers as soon as they're released, but also of having your documents correctly interpreted by search engines and other automated tools.
The URL for the HTML spec (with DOCTYPE info and current status on HTML revisions) is at [w3.org...]