Collectability: here, there are three categories. Firstly, biometric collection without needing a person's cooperation (indicated as 'high' in Table 4.1). Secondly, biometric collection that requires a degree of cooperation (indicated as 'medium' in Table 4.1), and, thirdly, biometric collection that requires more-complex collection techniques (indicated as 'low' in Table 4.1). Biometrics exhibiting high collectability can often be achieved covertly (i.e. without a person's knowledge or consent).
