|  | 
        A type X meets the GettableSocketOption requirements if it
        satisfies the requirements listed below.
      
        In the table below, a denotes
        a (possibly const) value of type X,
        b denotes a value of type
        X, p
        denotes a (possibly const) value that meets the Protocol requirements, and s denotes a (possibly const) value of a
        type that is convertible to size_t
        and denotes a size in bytes.
      
Table 20. GettableSocketOption requirements for extensible implementations
| expression | type | 
                  assertion/note | 
|---|---|---|
| 
                   | 
                   | 
                  Returns a value suitable for passing as the level
                  argument to POSIX  | 
| 
                   | 
                   | 
                  Returns a value suitable for passing as the option_name
                  argument to POSIX  | 
| 
                   | 
                   | 
                  Returns a pointer suitable for passing as the option_value
                  argument to POSIX  | 
| 
                   | 
                   | 
                  Returns a value suitable for passing as the option_len
                  argument to POSIX  | 
| 
                   | 
                  post:  |