ISO/IEC TR 18268:2013 presents a collation of industry experience of technical issues resulting from the presence of multiple PICCs (proximity card or object) in the field of a PCD (proximity coupling device). It describes how resonance frequencies may shift, how individual PICCs may see a reduced field strength, how multiple PICCs load the PCD, how they may change the local modulation signal and how PICCs should manage their identities to aid support of simultaneous usage. Scenarios for electronic passports with multiple visas and wallets containing multi-industry cards are explored.