Word – Prefixing heading numbers with custom letters, varying by section, in Microsoft Word

By default, Microsoft Word comes with default heading styles (e.g. Heading 1, Heading 2, Heading 3….).

These defaults can be changed based on need. For example, I modified the default headings to look like this:

So now I have a document that is structured like:

    1. Content
    1.1 Content
    1.2 Content
    1.2.1 Content
    2. Content
    2.1 Content
    2.1.1 Content
    2.1.2 Content
------ section break -------
    3. Content
    3.1 Content
    3.2 Content
    3.3 Content
    4. Content
------ section break -------
    5. Content
    5.1 Content
    5.2 Content
    5.3 Content
    5.3.1 Content

Each of the major areas of content are separated by sections. So, for purposes of this illustration, let's say I have 2 section breaks in this document separating 3 main areas of content.

However, what I need to do is restart the numbering at the beginning of each section and put a custom prefix is front of those numbers. Like this:

    X1. Content
    X1.1 Content
    X1.2 Content
    X1.2.1 Content
    X2. Content
    X2.1 Content
    X2.1.1 Content
    X2.1.2 Content
------ section break -------
    XI1 Content
    XI1.1 Content
    XI1.2 Content
    XI1.3 Content
    XI2 Content
------ section break -------
    XII1 Content
    XII1.1 Content
    XII1.2 Content
    XII1.3 Content
    XII1.3.1 Content

I tried doing this with the simple command sequence of "Restart Numbering" and "Set Numbering Value", but if you are using numbered headers, it won't let you put a letter prefix in front of it.

Let's say I have up to three levels per section — x, x.x, x.x.x — my thinking is that I need to create 3 custom heading styles per section for a total of, in this example, 9 custom heading styles (if my math is right). I was hoping there was an easier way than that.

Any suggestions?