autogenerating order numbers in access97

the admin department want a database of customer enquiries on the network, so that anyone taking an enquiry can add it to the database. so far, so easy. however they want to keep the numbering system they already use (yy/mm/0000). is there any way of automatically generating a number in this format whenever anyone opens the AddNewRecord form? – in words of one syllable please, i do networks, not databases (duh!)