Is there any reason to consider XHTML related details for web development for someone who works with HTML4 and plans to work with HTML5?
Or was XHTML a “side” development in web technology which is not related to the current mainstream of web development (which I guess is HTML5)?
Rationale for asking
The reason I’m asking is that a StackOverflow answer I previously posted was recently commented on to the effect that “You should NOT use upper case HTML tags”. When I asked “why” the commenter pointed me to a couple of articles, both of which gave the reasoning for lowercase-only tag names as “Upper case tag names are not allowed in XHTML” as the main reason.
Since I don’t currently do web development in XHTML (pure HTML4.0) and only plan to use HTML5 as the next step, I’m interested in whether XHTML should be a factor in assorted decisions I make as far as web development
Please note that this question is NOT asking whether one should use upper or lower case tag names in pure HTML – merely whether the upper-case-tag prohibition in XHTML should be a factor in my decision making, or I should ignore XHTML related rules.
Most of the info you will find on XHTML fails to mention that the whole purpose of XHTML is to be used by both humans and computers for data exchange. XHTML was created so that computers could talk to each other, but in the same time remain readable by humans.
The most crazy thing is that various code monks became obsessed with XHTML compliance, without any intend of using the XHTML for data exchange and without understanding what XHTML actually is.
Edit:
A good example of XHTML use is an airline company publishing its flights. The company can utilize XHTML to produce a single list of flights that will be both consumable be humans visiting online and by services that will read the data for their needs.
On the other hand if you own a hair-salon, there is no need for your site to validate against XHTML standards.