The minimum SDK version that your application can support. API level 9 only supports limited tag dispatch via ACTION_TAG_DISCOVERED, and only gives access to NDEF messages via the EXTRA_NDEF_MESSAGES extra. No other tag properties or I/O operations are accessible. API level 10 includes comprehensive reader/writer support as well as foreground NDEF pushing, and API level 14 provides an easier way to push NDEF messages to other devices with Android Beam and extra convenience methods to create NDEF records.