Another way, however, is for them to coordinate negotiation on particular headings ad hoc. All that the GATT requires for such coordinated negotiation is that each member of the bloc offer reciprocation for the concession so obtained. What they find is that, by acting in concert, blocs of SSA countries would have a few more negotiating rights and a somewhat greater degree of internalization. One theoretical complication is multiple bloc membership. For the countries with multiple bloc membership would need to decide with whom to combine.
Negotiations are, almost by definition, about reciprocity.
When SSA negotiators approach those from the EU to negotiate on the principal supplier headings just identified, the latter will seek reciprocity in headings for which the EU is the relevant SSA country's or group's principal supplier. Wang and Winters find that SSA matters to the EU in a mercantilist sense in some trade headings. Considering the preferences granted to SSA countries under the GSP and Lom Convention , Wang and Winters conclude that they seem to confer little benefit on the latter. They are not particularly deep quantitatively, but to the extent that they are effective they are probably perverse. To be sure, preferences transfer some tariff revenues from OECD tax payers and other exporters to SSA exporters, but they do so in ways that could subvert long-run development.