submission before

hello all. I've a question that i might think is not much related with PHP, even the pages are PHP and everything is working with PHP. I've a FORM in my site to be written by the user, but, i need to know before the value of a field to fill another field in the form depending with the value of the previous field. i could put just the field i need filed and then, the user submit the value and i can after that fill the next field becase of the information from the previous field. example: FIELD 1: some text - the user press enter, and the next field is filled regarding the information from these field. how can i accomplish this ?? FIELD 2: Another FIELD: submit button cheers -- bvsantos@hal.min-saude.pt -- Divisao de Informatica informatica@hal.min-saude.pt Tel: +351 272 000 155 Fax: +351 272 000 257 -- Hospital Amato Lusitano Av. Pedro Alvares Cabral 6000-085 Castelo Branco geral@hal.min-saude.pt Tel: +351 272 000 272 Fax: +351 272 000 257