|  | 
        A type X meets the SettableSocketOption requirements if it
        satisfies the requirements listed below.
      
        In the table below, a denotes
        a (possibly const) value of type X,
        p denotes a (possibly const)
        value that meets the Protocol requirements, and u denotes an identifier.
      
Table 28. SettableSocketOption 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  |