Car insurance

Can anyone explain to me what the following means on a car insurance document:

"Degre de personnalisation a posteriori arrete au plus tard au 31/12/2003 conformement au chapitre X de l'annexe de l'AR du 14/12/92"

I can translate some of this as " Degree of personalisation a posteriori ????ending at the latest on 31/12/2003 in accordance with chapter X of the annexe of the royal decree of 14/12/92....but what does it mean?

Thanks