Including Running Headers or Footers Across Files
Running headers or footers typically correspond to source text within the same file. For example, if a running header refers to source text tagged with the paragraph tag ChapterTitle, that source text is displayed in the header for that file.
This feature works only for the same file, not across files. Suppose that you broke one file into two files and combined them using a book file. If ChapterTitle is a paragraph tag used for the chapter title, and it’s referenced in the running header, the chapter title will not show up in the header of the second file if no text is tagged with ChapterTitle in the second file.
In order to get the chapter title from the first file to show up in the header of ...