General Surveillance (GS) needs initially to address potential large-scale cultivation of GMP's in future and ? depending on the rate of market introduction ? small and scattered sites where potential adverse environmental effects on and outside of fields may occur. GS Networks should focus on selected landscape sectors that represent mosaics of cultivated GM- and non-GM-fields including potentially affected non-cropping areas as typical for landscapes dominated by agriculture. Due to complexity of agricultural environments and cost effectiveness, any selection of GS sites should follow a 'best-fit-principle', that is site selection depending on the (a) intensity of cultivation of the crop in question ? and (b) highest proportion of potentially affected non-cropping areas. This approach is suitable for detection of potential unanticipated volunteerism and ferality of crop species which harbour a natural potential for gene escape due to (i) invasion of disturbed areas outside cultivated fields, (ii) naturalisation as volunteers due to seed dormancy and establishment of soil seed banks, or (iii) hybridisation and introgression with special wild relatives.