the sources are 1.5.3 and if you went through them you would know that..
I suppose that 16-bit addressation means that there are limitations related to 16-bit constants: e.g. the maximum level which server supports is 32767 (16-bit signed limit), the maximum ID of a quest is 65535 (16-bit unsigned limit),...PW has been 64bit since 1.5.2 I believe. there have been x64 and x86 clients in the folder for a while
I suppose that 16-bit addressation means that there are limitations related to 16-bit constants: e.g. the maximum level which server supports is 32767 (16-bit signed limit), the maximum ID of a quest is 65535 (16-bit unsigned limit),...
If I'm wrong, please somebody correct me.