Insert the relevant part of the original MCNET guidelines file int our own...

Insert the relevant part of the original MCNET guidelines file int our own USING_COLLABORATING.md file.

USING_COLLABORATING.md

@@ -38,5 +38,64 @@ the build system to what extent this code is used to build CORSIKA.
 ## Contributing
 
 If you want to contribute, you need to read
-[the GUIDELINES](CONTRIBUTING.md) and comply with these rules, or help to
+[the contributing GUIDELINES](CONTRIBUTING.md) and comply with these rules, or help to
 improve them. 
+
+
+## General guidelines
+
+We reproduce below some guidelines copied from  http://www.montecarlonet.org/ that we also ask you to follow in the spirit of academic collaboration.
+
+1) The integrity of the program should be respected.
+    -------------------------------------------------
+
+1.1) Suspected bugs and proposed fixes should be reported back to the
+    original authors to be considered for inclusion in the standard
+    distribution.  No independently developed and maintained forks
+    should be created as long as the original authors actively work on
+    the program.
+
+1.2) The program should normally be redistributed in its entirety.
+    When there are special reasons, an agreement should be sought with
+    the original authors to redistribute only specific parts. This
+    should be arranged such that the redistributed parts remain
+    updated in step with the standard distribution.
+
+1.3) Any changes in the code must be clearly marked in the source
+   (reason, author, date) and documented. If any modified version is
+   redistributed it should be stated at the point of distribution
+   (download link) that it has been modified and why.
+
+1.4) If a significant part of the code is used by another program,
+    this should be clearly specified in that program's documentation and
+    stated at its point of distribution.
+
+1.5) Copyright information and references may not be removed.
+    Copyright-related program messages may not be altered and must be
+    printed even if only a part of the program is used. Adding further
+    messages specifying any modifications is encouraged.
+
+
+2) The program and its physics should be properly cited when used for
+    academic publications
+    ------------------------------------------------------------------
+
+2.1) The main software reference as designated by the program authors
+    should always be cited.
+
+2.2) In addition, the original literature on which the program is based
+    should be cited to the extent that it is of relevance for a study,
+    applying the same threshold criteria as for other literature.
+
+2.3) When several programs are combined, they should all be mentioned,
+    commensurate with their importance for the physics study at hand.
+
+2.4) To make published results reproducible, the exact versions of the
+    codes that were used and any relevant program and parameter
+    modifications should be spelled out.
+
+
+(These guidelines were originally edited by Nils Lavesson and David Grellscheid
+for the MCnet collaboration, which has approved and agreed to respect
+them.  MCnet is a Marie Curie Research Training Network funded under
+Framework Programme 6 contract MRTN-CT-2006-035606.)