# Class Netchannels.output_descr

    class output_descr : ?blocking:bool -> ?start_pos_out:int -> Unix.file_descr -> raw_out_channel

Creates a `raw_out_channel` for the passed file descriptor, which must be open for writing.

The `pos_out` method returns logical positions, i.e. it counts the number of written octets. It is not tried to determine the real file position.

The method `close_out` also closes the file descriptor.

This class also supports Win32 proxy descriptors referring to an output channel.

`blocking` : Whether the channel waits until it can output if it is not possible to write to the (non-blocking) descriptor. Defaults to `true`.
`start_pos_out` : The position to which `pos_out` is initialized when the channel is created, by default 0