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The Frame Status consists of 3 indicators which may have one of two values. The indicators can either be Set ('S') or Reset ('R') (the indicators could also be corrupted; a corrupted indicator is neither 'S' nor 'R'). Every frame is originally transmitted with all of the indicators set to 'R' (reset). The indicators can be set by intermediate stations when they retransmit the frame. The three indicators are: Error ('E'), Address recognized (or Acknowledge) ('A'), and Copy ('C'). Error: This indicator is set when a station determines that the frame is in error. This may be due to a format error, or to a failure of the CRC. If a frame is received and the 'E' indicator is anything other than Reset ('R'), then that frame is disregarded. Acknowledge: This indicator is set by a station when it receives the frame and determines that the address applies to itself. This could be because the destination address of the frame is the MAC address of the station, or because the destination address of the frame is a broadcast address. Copy: This indicator is set when the station receives the frame and is able to copy the contents into its buffers. Most stations do not copy the contents unless the frame is explicitly destined to them (or broadcast), so the 'A' and the 'C' indicators are usually set at the same time. However, sometimes a station will be receiving so much traffic that it cannot copy all the information to its buffers even though the frame is destined to it. In this case, it would retransmit the frame with the 'A' indicator set, but the 'C' indicator will remain reset.
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