Question re: TechTrade tag in CvTeam

Hi guys. I have a question to ask regarding the <bTrade> tag in CvTechInfos. I want to add a tag called <bFirstTrade>, the idea being that you can only trade the tech if you are the first to research it.
Now, adding it to CvTechInfos was easy enough, but I am having trouble locating the Trade function in CvTeam. Can anyone tell me where I can find this function? Because finding it is the first step towards adding the FirstTrade function. Please help me guys !

Aussie_Lurker.

The xml-tag bTrade is the variable m_bTrade in the SDK. Searching for that variable I found the method CvTechInfo::isTrade() which is returning the value of m_bTrade. isTrade() is only once used, in CvPlayer::canTradeItem().
Well that's all, go and change canTradeItem().

Matze