802.11 MAC frame

Hi,

In 802_11.h file in /usr/include/linux shows the following structure
for 802.11 MAC frame

struct ieee_802_11_header {
u16 frame_control;// needs to be subtyped
u16 duration;
u8 mac1[6];
u8 mac2[6];
u8 mac3[6];
u16 SeqCtl;
u8 mac4[6];
u16 gapLen;
u8 gap[8];
};

Now I have a question about last two fields. They don't appear in the
frame formats I found on internet. One of them is at
http://einstein.informatik.uni-olden...etze/frame.htm

What do gapLen and gap stand for ? What I know is that after 4th address
(mac4[6]) there is databody.


Regards,
Tejas Kokje
University of Southern California
Los Angeles