Constant buffer sequences requirements

A constant buffer sequences range represents a set of datagrams that may be used as input to an operation, such as the send_multiple operation of a datagram socket. Each element describes the memory regions of one datagram.

A type X meets the ConstBufferSequences requirements if it satisfies the requirements of Destructible (C++Std [destructible]) and CopyConstructible (C++Std [copyconstructible]), as well as the additional requirements listed below.

In the table below, x denotes a (possibly const) value of type X, or of type R if X is std::reference_wrapper<R>.

Table 12. ConstBufferSequences requirements

expression	return type	assertion/note pre/post-condition
`x.begin()` `x.end()`	A type meeting the requirements for forward iterators (C++Std [forward.iterators]) whose value type meets the `ConstBufferSequence` requirements.	[`x.begin()`,`x.end()`) is a valid range. The range may be traversed more than once.