I am using a customized axdocbook as a MIL-STD technical bulletin.
I need the header/footer to populate the classification level of the individual pdf page. If any element has the attribute classification=secret, I need SECRET to appear in the header/footer. If no elements on the page are secret (meaning they do not have a classification attribute or have classification=unclassified), I need SECRET<newline/>(THIS PAGE IS UNCLASSIFIED) to appear in the header footer.
I have been able to conditionalize the gentext for the individual elements based on this attribute (to apply (S) or (U) before the element's content and so on). However, I do not know how to conditionalize the content in a header or footer.
I don't think you'll be able to do this. At least not easily.
There are several reasons for this. Not the least is a classified paragraph could carry over to another page but the only marking on that page is unclassified. Another problem (and XSL should be able to manage) is a preceding page is unclassified but the following page is classified, but at a level lower than the highest (e.g. confidential in a secret manual) classification. The style sheet would have to read ahead (multiple passes would work).
I would opt for the option in 5200.01M Vol 2 (para 5c(1)) that allows all pages to be marked at the highest level.