Sony Xperia XZ2 Manual page 197

reading and writing radio communication equipment under the Radio Law.
These features use the 13.56 MHz frequency band. Distance adequately from other reader/writer,
P2P devices if being used nearby. Also make sure that other wireless radio stations using the same
frequency band are not nearby.
Before using aboard an aircraft, check with the airline beforehand. Use may be restricted depending
on the country. Be sure to check laws and other conditions of the country/region.
Designation can be viewed in the following way.
To view: in Home Screen,
xperia-xz2_14_Safety Precautions.docx
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(Apps) (Settings) System About phone Certificates