G06K 7/10247

Methods or arrangements for sensing record carriers, {e.g. for reading patterns} by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation {sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves the reader and the record carrier being capable of selectively switching between reader and record carrier appearance, e.g. in near field communication [NFC] devices where the NFC device may function as an RFID reader or as an RFID tag issues specific to the use of single wire protocol [SWP] in NFC like devices}