According to the National Staff, the bat rule will continue has it finished last year. The only change is that no alloy is specifically prohibited by rule.
The manufacturers have "supposedly" (I don't trust them at all) given ASA a list of all models manufactured before 1996 and they are "supposedly" included on the lists located on ASA's web site,
http://www.softball.org.
The umpire maintains the authority to allow any bat which s/he believes meets the criteria which would make it a legal bat.
BTW, the ASA is the rule book for ALL games played under ASA rules. Local associations have the authority to variate from these rules as they see fit. However, when doing these games, the ASA rule book should be your default concerning any not specifically noted by the local authorities.
Mike