For example here:
https://github.com/cppalliance/http_proto/blob/develop/include/boost/http_proto/serializer.hpp#L340

        Initializes the serializer with the HTTP
        start-line and headers from `m`, and returns
        a @ref stream object for reading the body
        from an external source.

This should say "writing the body" because we always word things from the perspective of the remote peer. That is, we write the body (to the remote peer). We read the body (from the remote peer). Serializer is used with asio::write for example. We don't use asio::read, as that is for parser.