Yes, Allow HTML is allowed as per screenshot Capture1
Once allowed I'm not getting the invalid variable error but it redirects the browser to www.mydomain.com/index.php"%20target="_blank which is wrong.
I think the issue is I'm not sure if I'm writing the " target="_blank at the right place.
Should it go on the URL field? I tried both with " and without it. Or should I place it somewhere else.
I already checked the JQuery option, but having t hardcoded will not be easily maintenable for a new site (things will change, options added and deleted, so I should be playing around with the code). Probably once the site is stable.