Developer credits
Git commits in Moodle 2.6.3 by James Pratt
commit 6569d675f169be4f199090eafbbf5498d0639788 Author: James Pratt <me@jamiep.org> Date: Fri, 11 Apr 2014 14:36:15 +0800 Tag: v2.6.3 MDL-44981 quiz statistics report : Differentiating '0' and no response
commit 9cf2bc9d3fa9a0a399778e2402d24a6f94c1bc5a Author: James Pratt <me@jamiep.org> Date: Fri, 11 Apr 2014 11:53:34 +0800 Tag: v2.6.3 MDL-45003 qtype numeric : classify invalid response as no response.