May I add this to Terry's post...
The Rules are not being changed. The dimensions are as they have always been. However, there is also a Rule that says that cells may be up to 44mm long AFTER charging, so that any distortion of the cell is taken into account. This was put in because some cells did distort (look at the base of the cell, they 'bell' out a bit on some) and it was not BRCA/EFRA's intention that drivers were disqualified because of something largely outside their control.
However, some cell manufacturer's took liberties, and made cells that 'borrowed' length from the 44mm Rule. BRCA/EFRA seem to have decided that they should go back to the 43mm Rule, including any distortion.
This change was made in 2006, and it was posted in the Rule books (EB Rule 3.1, EFRA Rule Appendix 3 - 3.1). It has been coming for 14 months, and now it is here. Orion have noticed this, and have developed a cell that seems to be (only pictures posted so far) about 42.4mm long, allowing for any distortion to keep the cell under 43mm.
So, it isn't a sudden change, and arguably it isn't retrospective. However, no one can say they weren't warned! Whatever your view, it wouldn't surprise me to find that the new list effective from 1 April 2008 does not have cells on it that cannot comply to the original Rules, including the removal of the '44mm allowance' agreed and published in 2006. HTH
