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Oxygen PDF Chemistry provides a CSS extension, oxy_xpath, that can be used to execute XPath functions, including the fn:current-date function that simply returns the current date.

For example, if the text of the title is set in a booktitle element, you can use a synthetic block with the date content like this:
    booktitle:after {
        content:oxy_xpath("current-date()");
        color:gray;
        display:block;
    }