Out-of-band data | Article about out-of-band data by The Free Dictionary
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out-of-band dataData transmitted with the primary data stream that is considered a control signal and which demands immediate attention. The receiving side must pass the out-of-band (OOB) data to the appropriate software routine in front of any other data that has been buffered and not yet processed, because the command must be executed as soon as possible. See signaling in/out-of-band.