|  | 
        In the table below, a denotes
        an asynchronous random access read device object, o
        denotes an offset of type boost::uint64_t,
        mb denotes an object satisfying
        mutable buffer sequence
        requirements, and h denotes
        an object satisfying read handler
        requirements.
      
Table 4. Buffer-oriented asynchronous random-access read device requirements
| operation | type | semantics, pre/post-conditions | 
|---|---|---|
| 
                   | A type satisfying the Executor requirements. | Returns the associated I/O executor. | 
| 
                   | 
                   | 
                  Initiates an asynchronous operation to read one or more bytes of
                  data from the device  |