what does sh ima interface command on router mean

did  this command on router   -sh ima interface    

 
Interface ATM0/IMA0 is down
        Group index is 50
        Ne state is startUp, failure status is configAborted
    IMA Group Current Configuration:
        Tx/Rx minimum required links 1/1
        Maximum allowed diff delay is 25ms, Tx frame length 128
        Ne Tx clock mode CTC, configured timing reference link ATM0/0/0
        Test pattern procedure is disabled
    IMA Group Total Counters (time elapsed 0 seconds):
        0 Tx cells, 0 Rx cells
        0 Ne Failures, 0 Fe Failures, 43662 Unavail Secs
    IMA link Information:
        Link     Physical Status        NearEnd Rx Status      Test Status
        ----     ---------------        -----------------      -----------
        ATM0/0/0 down                   unusableFailed         disabled
        ATM0/0/1 down                   unusableFailed         disabled

Can some one explain we what doe ATM0/0/0 means??????????????