[TYPO3-english] Parameters on links

[Sergio Catalá Gil]

I made progress about the issue:

extra_info {
		field = generic_tx_mblnewsevent_extra_info
		value = http://www.anothersite.com/events/ 
 		typolink {
			parameter = http://www.anothersite.com/events/{DB:tt_news:6408:tx_mblnewsevent_pk}/join
			parameter.insertData=1
 			title = Click here to see the link
 		}
 	}
}

Now I would like to change typolink.parameter like this:

parameter = http://www.anothersite.com/events/{DB:tt_news:{GPvars:tx_ttnews|tt_news}:tx_mblnewsevent_pk}/join

But I'm not allowed to use nested brackets for the expression :-(

Any hint?

Thanks in advance, 
Sergio