
Source: http://www.ncfe.org.uk/download/qualspec/100-6039-X-qualspec.pdf [1] page 11
Links
[1] http://www.ncfe.org.uk/download/qualspec/100-6039-X-qualspec.pdf
[2] http://theingots.org/community/node/14959
[3] http://theingots.org/community/node/15697
[4] http://theingots.org/community/node/15698
[5] http://theingots.org/community/node/13482