Seeking clarification of documentation around writting values

[digispiders]

Documentation as written:

writevalues   List of values to be written.
                If none specified (default) mbpoll reads data.
                If negative numbers are provided, it will precede the list of
                data to be written by two dashes ('--'). for example :
                mbpoll -t4:int /dev/ttyUSB0 -- 123 -1568 8974 -12

Can you clarify how this specifies address and number. For instance, in the above, is 123 the address, and -1568 the data to be written?