See here (https://mortem-et-gloriam.co.uk/smf/index.php?topic=3779.0).
Change "Cv, Cm, Ch and Elephants cannot claim +4 for flank (but not rear) charge against Elephants."
With the current rules, cavalry, chariots or camelry charging Elephants in the flank get +4 for the flank charge in addition to any other claims. Elephants get +4 for fighting elephants and +4 for the flank - basically +8!". This reduces the flank charge effect.
Note: It doesn't affect infantry flank charging elephants or any rear charges.