The ISO standard for Prolog is ISO/IEC 13211-1:1995. Copies can be
purchased from national standards bodies (e.g. ANSI, AFNOR, DIN). 
It defines the core features of Prolog: part 2, in preparation, 
will define modules. ISO does not currently make standards available 
by anonymous FTP, but the 1993 draft ISO standard for Prolog is
available by anonymous FTP from
   ai.uga.edu:/pub/prolog.standard/ [128.192.12.9]
An unofficial summary of the ISO Prolog standard is available
from the same location as isoprolog.tex or isoprolog.ps.Z.  Send mail
to Michael Covington <mcovingt@ai.uga.edu> for more information about
his summary of the standard. 

A PostScript version of the August 1995 draft for Part 2 is
available from
   http://www.sju.edu/~jhodgson/x3j17.html

For more information about the ISO Prolog standardzation, write to
Roger Scowen, ISO/IEC JTC1 SC22 WG17 (Prolog) convener, 9 Birchwood
Grove, HAMPTON, Middlesex TW12 3DU, UNITED KINGDOM, 
phone +44-181-979-7429, fax +44-181-287-3810, 
or, preferably, send email to rss@ditc.npl.co.uk.

Richard O'Keefe's 1984 Prolog standard draft is available by anonymous
FTP from 
   ftp.ecrc.de:/pub/eclipse/std/plstd.doc

Some parts © 2009 Advameg, Inc.