My friend I can also think other approaches.

I don't doubt that. But you need a working solution. I gave you one.

True.

Often the direct answer isn't really helpful. I try to help. Sometimes helping means to tell people that in my opinion they need to abandon their original plan. And since this is a free forum people are free to ignore my opinion.

I've seen this post since I did follow your link in your previous post. If I remember correctly spocke's reply is over a year(!) old. And if I also remember correctly most of the documentation is generated automagically - apparently (for what reason?) just not this option. This makes me wonder...

So I gave you a viable alternative since you obviously need a working solution.

So, all considered, was I not helpful?

I solved my problem by using an alternative (span[style<text-decoration: underline;]).
Your solution, is also a nice one, but it needs to change the underline format in order to work as i need, and i don't know if pasting from word (or generally pasting)would auto transform it to this format (<span class="underline-class">).
So because there is no time for test, i used my first option. Thanks a lot for the help, but please try to answer what someone asks (my main question was why is valid_styles not working {here http://www.tinymce.com/forum/viewtopic. … 101#p76101 MAIN DEVELOPER suggests to use it and says it has to be documented})

My approach would have worked, if valid_styles worked the way expected. And this is the main goal of valid_styles. To filter styles!!!

Maybe this is the reason why it still hasn't been documented...?

I strongly suggest you rethink your approach. But you don't have to heed my advice of course.

From as far as you can see from this post, this option exists a lot time, but it has stayed undocumented for an unknown reason.
My approach would have worked, if valid_styles worked the way expected. And this is the main goal of valid_styles. To filter styles!!!

I am not asking how to do something but, why something is not working.

Maybe this is the first obstacle to finding a solution?

I'm not familiar with this configuration option. The wiki doesn't list it. I also couldn't find any plugin to provide such an option.

So what made you think your approach could work?

So why this is not working as it should?
Thanks a lot for the quick answer but I hope the next will be more relevant to what I ask.

A solution to purely visual issues should use CSS. You either define a certain class (let's call it "marked") as in these two examples:

<p>This is <span class="marked">marked content</span> for better readability.</p>
<p class="marked">Sometimes everything is so important that people simply must highlight it.</p>

Your CSS could then make use of this class name:

.marked { text-decoration: underline; }

But this is all basic HTML/CSS knowledge. Why wouldn't you want a solution like this?

I would like to force my clients to use U and S tags rather than inline styles because I don't want them to have arbitrary control over the formatting of the page.

Using deprecated elements is NOT the best way to go. Why not use special class names and do the rest using CSS?

Why kill the messenger when you have a problem with the message? Removing <span> elements just because of an unwanted attribute is a little harsh, don't you think? Why not remove style attributes instead?

This is a very weak argument. Browsers parse tag soup. That is one thing. Having standards-compliant code is another.

The deprecated tags are deprecated because they have nothing to do with semantics! So there is no "old semantic tag"! The tags in question (<s> and <u>) have the sole purpose of changing the visual representation. Other than that they carry no meaning, hence no semantics!

So, be flexible then! Think of more sophisticated ways to achieve your visual goal while still producing standards-compliant code!

Why? Either you should use modern tags or not. The only reason why someone should use the legacyoutput plugin is if there is compatibility issues with the HTML with rendering on Flash or in old mail clients.

Actually, that's not at all true.

I would like to force my clients to use U and S tags rather than inline styles because I don't want them to have arbitrary control over the formatting of the page.  I want them to be able to underline and strike-through text, but not set the font color or the font face, for example.  So, I have a post-processing filter that I use to strip out SPAN tags and many others.

Deprecated HTML tags are rarely ever remove from browsers.  There should be a nice easy switch to turn on "old" semantic tags rather than inline styles.  I agree that being "standards compliant" is important, but so it being flexible.

tinyMCE.init({
    ...
    formats : {
        underline : {inline : 'u', exact : true}
        }

...