NNTP extension to retrieve article headers using selection criteria. 

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The range of articles to be searched is specifies by the AParm argument. AParm must be in the following forms: 

For example, if the following values of AParm would result in the corresponding action: 

XHDR relies on the OnXHDREntry event handler to signal receipt of an XHDR response the NNTP server. An EIdNNTPNoOnXHDREntry is raised if the OnXHDREntry event handler is unassigned during a call to XHDR. 

You must have previously executed the SelectGroup command in order for this command to return a meaningful response. 

Article numbers are transitory. This means that you may specify a range of article numbers, such as 1-5, and you may receive only articles 1,3 and 4. This does not mean you have done anything wrong. The missing articles may have been expired (removed from the server), or for some other reason not under your control have become unavailable.

procedure XHDR(
    AHeader: string; 
    AParam: string
); overload;