sql execute elapsed time in Time Model Statistics

Hi,
in this example:

sql execute elapsed time                      850,978.51    84.34
DB CPU                                        281,499.15    27.90
parse time elapsed                             50,735.63     5.03
PL/SQL execution elapsed time                  21,929.18     2.17
connection management call elapsed time        20,699.89     2.05
hard parse elapsed time                        15,309.50     1.52
PL/SQL compilation elapsed time                   559.19     0.06
hard parse (sharing criteria) elapsed time        366.26     0.04
failed parse elapsed time                         188.63     0.02
sequence load elapsed time                         92.84     0.01
hard parse (bind mismatch) elapsed time            17.69     0.00
repeated bind elapsed time                         15.75     0.00
RMAN cpu time (backup/restore)                      0.72     0.00
DB time                                     1,008,985.78         
background elapsed time                       111,559.54    
background cpu time                             4,465.04    


281,499.15    seconds of cpu was spent on the database.  
1,008,985.78  seconds of service time (db cpu + wait time) was spent on the database

it mean that  wait time = 1,008,985.78 - 281,499.15 = 727,486.63 .....?

how 850,978.51 of "sql execute elapsed time" is calculated ....?