@AlanHK...

Deleting what from where? Deleting subheads from the NCX TOC or deleting subheads from within the xhtml files? I tested the plugin with a test file which used h1, h2 plus a third heading(formatted with h3) and there were no problems or deletions in the NCX or epub html. I also tested my plugin using a much larger and more complicated epub file that also used 3 heading levels -- including subheadings. The plugin didn't have a problem with either test file and there were no subheading deletions. Of course if you don't format the appropriate headings using just h1 and h2 styling then you will probably get problems. But that's all explained in the plugin release notes which I'm sure you've read already.

When you say configurable separator character do you mean being able to configure different font characters/symbols with different font sizes etc? That's not really necessary since you can easily reconfigure/restyle those separator characters manually anyway after you run the plugin. I always prefer to keep plugins simple -- and if you want to do something more exotic you can usually achieve those changes manually in the CSS or you can do it using grep S&R.

I had a toc with 3 levels of headings, as mentioned. Using the plugin combined level 1 and level 2, deleted level 3. Only affecting the ncx file, to clarify, the HTML files aren't affected.

This is the way the chapter headings were coded originally.
Using Sigil's generate TOC tool gives 3 levels of headings.
Then using the plugin combines h1 and h2 text in the TOC, and the h3 heads disappear.



The character.
I know there is no formatting in the NCX, at least no way I know of.

The plugin offers space, em dash, en dash, tilde as separator.
Many use period or colon, (Chapter 2: The Story Continues) but rather than add more and more symbols, etc., simplest just have a default and let user change it to whatever, preferably retained for next use.

@AlanHK...

"I had a toc with 3 levels of headings, as mentioned. Using the plugin combined level 1 and level 2, deleted level 3. Only affecting the ncx file, to clarify, the HTML files aren't affected."
I draw the line at combining h1, h2 and h3 simply because I doubt many people will want to combine 3 headings per NCX heading. In other words your idea of combining 3 levels -- h1, h2 & h3 -- is unrealistic because I'm guessing that not many people will use it. More likely, they will prefer to combine just h1 & h2 headings in the NCX TOC. Add to this that such a plugin change -- to combine h1, separator, h2 & h3 -- would also make plugin usage more complicated. As I've already mentioned, I like to keep it simple for the user.

"Using Sigil's generate TOC tool gives 3 levels of headings.
Then using the plugin combines h1 and h2 text in the TOC, and the h3 heads disappear."
What you describe above is correct behaviour for the plugin because the plugin is only meant to combine just the h1 & h2 headings in the NCX TOC. The plugin does not combine or add h3. In other words, only combining h1 and h2 headings is what the plugin is supposed to do as is clearly stated in the plugin release notes -- it's certainly not a plugin error as you seem to be inferring.

"I know there is no formatting in the NCX, at least no way I know of."
Actually you can both generate and edit/change the headings in the NCX TOC quite easily in Sigil. Just click on Tools > Table of Contents > Generate Table of Contents or Edit Table of Contents and then right-click and edit each heading as you like. In this way you can edit/change each NCX heading in turn by manually typing in and adding h1, h2 headings with a separator and even, if you like, adding h3 headings appropriately to each NCX heading. And when your done, just press OK and your epub's NCX TOC will automatically update to your new NCX TOC heading format. And you could probably also use grep S&R within the toc.ncx file to achieve the same outcome or result.

The error is not that it doesn't combine h1+h2+h3 but that it combines h1+h2 and DELETES h3.
That is damaging the book. If you more than two levels of headings, you can't use this plugin.

Not when I tried this.
Any codes you type into the the TOC editor get encoded and you just get visible code, not changes on format. e,g, adding <i> </i> to a heading, what I see is the literal codes and looking in the NCX what it did was

<text>&lt;i&gt;TIME AND THE GODS&lt;/i&gt;</text>

If I edit the NCX to make it <text><i>TIME AND THE GODS</i></text>
and then do "Create HTML TOC", the tags were not there. And epubcheck says

ERROR(RSC-005): Error while parsing file 'element "i" not allowed anywhere; expected the element end-tag or text'.

Anyway, not asking to insert any formatting into the NCX.
I leave that to the HTML TOC.
Just a choice of separator character.

@AlanHK...

"The error is not that it doesn't combine h1+h2+h3 but that it combines h1+h2 and DELETES h3. That is damaging the book. If you add more than two levels of headings, you can't use this plugin."
I'll have another look at that problem.

"<text>&lt;i&gt;TIME AND THE GODS&lt;/i&gt;</text>
If I edit the NCX to make it <text><i>TIME AND THE GODS</i></text>
and then do "Create HTML TOC", the tags were not there. And epubcheck says: ERROR(RSC-005): Error while parsing file 'element "i" not allowed anywhere; expected the element end-tag or text'. "
Why on earth would you ever expect Sigil's "Create HTML TOC" feature to allow you to format the text within the NCX TOC in the editor or directly within the toc.ncx file itself? Heck, the Create HTML TOC editor is a pure text editor for goodness sake -- it's not an html editor that will allow you to embed html code tags. Also, the toc.ncx file isn't an html file -- it's an XML file. You could perhaps add indents and alter the chapter headings to upper/lower/title case within the Create HTML TOC editor or within the toc.ncx file but that's about all you can do.

I didn't. Was pretty sure it would not work but you said

So presumably you meant "add the text of the h1, h2 headings", not the h1, h2 heading tags.

@AlanHK
In Sigil, if you open either the Tools > Table of Contents > Create TOC pop-up window then, if you want to capitalize, change text or add text to the displayed headings then all you have to do is just double click on any selected heading on the left and you can directly edit the text how you like. You can do that to all displayed headings but, as I've already mentioned, you cannot add html to those changes because it only allows text edits, not edits using html mark-up.

And I'm not sure whether you actually realize it but, due to a fairly recent Sigil change, you now have two ways to specifically edit the NCX TOC in Sigil. You can edit the TOC in the normal way using Tools > Table of Contents > Generate TOC and when you press "OK" this feature always creates an NCX TOC from scratch. But you can also now directly edit the existing NCX TOC(in the toc.ncx) by just clicking on Tools > Table of Contents > Edit TOC. And again this feature also allows you to directly change/edit heading text only(not html) and add indents. And when you click "OK" it automatically updates all your heading changes in the toc.ncx file.

Sure. I knew all that. Don't know why you thought I didn't.
I've been using "Edit TOC" and also directly editing the NCX for years.

We just seem to be not communicating well.

Update(v0.1.2):
Fixed a problem with sub-headings h3 - h6 not displaying in the TOC NCX after running the plugin. Thanks to AlanHK.

This plugin will now create a flat NCX TOC showing all headings formatted with h1 - h6. If you wish to add indents to your sub-heading entries in your NCX TOC, you can do this in Sigil using Tools > Edit Table of Contents in the normal way by selecting each of the relevant headings in turn and using the arrow keys on your keyboard to directly add/remove indents in the edit window as you prefer.