XHDR header [range|<message-id>]

    The XHDR command is used to retrieve specific headers from
    specific articles.

    The required parameter is the name of a header line (e.g.
    "subject") in a news group article. See RFC-1036 for a list
    of valid header lines. The optional range argument may be
    any of the following:
                an article number
                an article number followed by a dash to indicate
                   all following
                an article number followed by a dash followed by
                   another article number

    The optional message-id argument indicates a specific
    article. The range and message-id arguments are mutually
    exclusive. If no argument is specified, then information

    from the current article is displayed. Successful responses
    start with a 221 response followed by a the matched headers
    from all matched messages. Each line containing matched
    headers returned by the server has an article number (or
    message ID, if a message ID was specified in the command),
    then one or more spaces, then the value of the requested
    header in that article. Once the output is complete, a period
    is sent on a line by itself. If the optional argument is a
    message-id and no such article exists, the 430 error response
    is returned. If a range is specified, a news group must have
    been selected earlier, else a 412 error response is returned.
    If no articles are in the range specified, a 420 error
    response is returned by the server. A 502 response will be
    returned if the client only has permission to transfer
    articles.

    Some implementations will return "(none)" followed by a
    period on a line by itself if no headers match in any of the
    articles searched. Others return the 221 response code
    followed by a period on a line by itself.

    The XHDR command has been available in the UNIX reference
    implementation from its first release. However, until now,
    it has been documented only in the source for the server.

2.6.1 Responses

        221 Header follows
        412 No news group current selected
        420 No current article selected
        430 no such article
        502 no permission