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+# How to contribute
+
+mruby is a young open-source project.  
+
+We are looking forward to each pull request. 
+
+## Pull Request
+
+To make it easy to review und understand your change please keep the following
+things in mind for your pull request:
+
+* Make you change on the latest possible state of +mruby/master+
+* Test your changes before creating a pull request (+make test+)
+* If possible write a test case which confirms your change
+* Don't mix several features or bug-fixes in one pull request
+* Create a branch which is dedicated to change
+* Create a meaningful commit message
+* Explain your change (i.e. with a link to the issue you are fixing)
+
+## Coding conventions
+
+How to style your C and Ruby code which you want to submit.
+
+### C code
+
+The core part (parser, bytecode-interpreter, core-lib, etc.) of mruby is
+written in the C programming language. Please note the following hints for your
+C code:
+
+#### Comply with C99 (ISO/IEC 9899:1999)
+
+mruby should be highly portable to other systems and compilers. For that it is
+recommended to keep your code as close as possible to the C99 standard
+(http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf).
+
+Although we target C99, VC is also an important target for mruby, so that we
+avoid local variable declaration in the middle.
+
+#### Reduce library dependencies to a minimum
+
+The dependencies to libraries should be put to an absolute minimum. This
+increases the portability but makes it also easier to cut away parts of mruby
+on-demand.
+
+#### Don't use C++ style comments
+
+    /* This is the prefered comment style */
+
+Use C++ style comments only for temporary comment e.g. commenting out some code lines.
+
+#### Insert a break after the method return value:
+
+    int
+    main(void)
+    {
+      ...
+    }
+
+### Ruby code
+
+Parts of the standard library of mruby is written in the Ruby programming language
+itself. Please note the following hints for your Ruby code:
+
+#### Comply with the Ruby standard (ISO/IEC 30170:2012)
+
+mruby is currently targeting to execute Ruby code which complies to ISO/IEC
+30170:2012 (http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=59579).