XDOCINFO is used to get the head information of 
a http URL only.

Example

XDOCINFO
http://www.ictp.trieste.it

The above example will only return information about the page
as provided by the web server.

XDOCINFO can also be used to set the maximum file size limit 
to a value below the www4mail maximum file size limit. 

Example
XDOCINFO 1M
ftp://ftp.somesite.com/really_large_file

The above example will will not send you the file if it is 
larger than 1M bytes.

SEE ALSO 
help limits
help getsize


NOTES:
Case 1 can be used to get information about file types directly
from the WEB server.
Case 1 WILL only work for http requests, it will not work ftp or
other types of requests.