### Settable socket option requirements

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 pre/post-conditions
--- | --- | ---
`a.level(p)` | `int` | Returns a value suitable for passing as the level argument to POSIX `setsockopt()` (or equivalent).
`a.name(p)` | `int` | Returns a value suitable for passing as the option_name argument to POSIX `setsockopt()` (or equivalent).
`a.data(p)` | `const void*` | Returns a pointer suitable for passing as the option_value argument to POSIX `setsockopt()` (or equivalent).
`a.size(p)` | `size_t` | Returns a value suitable for passing as the option_len argument to POSIX `setsockopt()` (or equivalent), after appropriate integer conversion has been performed.