🚀 go-pugleaf

CW -- There are two solutions. 

I think the easiest is to use two user-defined variables. Since you want to pull the document title and the model number, and I would assume these would be the same throughout the book, I would just use two variables, say, DocTitle = Installation Guide and ModelNum = MOD123.  Then, where ever you need it in any file, you use DocTitle and ModelNum. You can enter it in the headers and footers, or even in the body and of course, right on the title page. 

The other way is to use a running H/F that pulls the text from a paragraph. So if you have a paragraph tag called Title and it contains Installation Guide, your running h/f could say <$paratext[Title]>. But the hassle with this is that Title must exist in every file where it's needed.