I've seen this
<http://emacs.stackexchange.com/questions/14320/org-mode-links-open-in-new-tab>
discussion,
but it doesn't really answer the question of how to have a link upon export
to HTML do a :target _blank (new tab). The given answer

#+ATTR_HTML: :target _blank

works exactly once -- for the link immediately following where you've stuck
it. Additional links thereafter do not get new tab behavior. Any way to
tell the whole file to do new tab upon left click of link?

LB