To add own table style to document template

Writer, LO 7.5.9

One follows Writer Guide 7.5, section Tools for working with tables > Creating a table style
Goal: To have own table style stored in own .ott file (Writer document template).
All table properties should be included in user-defined table style, incl. table/columns width

Steps conducted so far:
Open template for edition.
Insert table to template - this may be not necessary, however it helps me to see my formatting modification if those match my own expectation.
Table was inserted to template using Writer factory table style.
Proceed to Write Guide, the mentioned section, which means (a Tip in Guide) one should define table as AutoText in this case.
Hence Tools > AutoText gets open by template author.
Which category (wording used by Writer Guide) will best match the goal:
Only for Templates?
My AutoText?

Presently, “table styles” are not implemented as the other “real” style categories. Consider tables styles are rather a set of macros which are triggered in various circumstances, such as new row, new column, document global update. These macros are particularly stubborn and wipe out your intentional manual modification to cell formatting. Since they add direct formatting of their own, this overrides applied character styles and replaces your own direct formatting.

This is already enough not to use these “styles”.

Another point: if you change the so-called style, no update occurs on the existing tables creating with the style.

All in all, the feature is badly defined (and I don’t think there is any clear specification which could then be discussed). Don’ t expect table properties to be stored in some “style” like paragraph ones. You can’t control table “geometry” like that.

The only user-friendly method I found so far to create identically looking tables is to manually create one, adjust the properties, pre-style the cells and copy the resulting table into an AutoText entry.

An AutoText entry is considered a global document-independent object, like hyphenation dictionaries. It is then not stored in any document (a template is just another form of a document). You can’t then store AutoText entries the same as you store styles for later uses into templates (and as many templates with different contents for different usages as you need).

But, when you create AutoText entries, you can request they be saved in a file you choose. This file has special extension .bau and can be retrieved in the directory registered for AutoText (see Tools>Options, LibreOffice>Paths). AutoText entries are immediately available for all documents, even for existing ones, templated or not. Knowing where .bau files end up allows you to retrieve them for backup in your preferred directories in case some unfortunate event causes a user profile reset.

And, yes, an AutoText entry is not a style. You can’t tune it by modifying it. Existing tabled can’t be changed by changing the AutoText; you must applied the changes manually or recreate the table.