UserInformixInfo.Password silent response option

Can anyone tell me what the -W UserInformixInfo.Password= option in the informix 11.50 .ini silent response file does? I searched the documentation on the Informix Information Centre but can't see it documented anywhere. I noticed in some of the installer documentation that the installer can create the informix user and group if neither already exist on the unix server. If I set a value for this option, will it create the user and group for me? If not, is there any other way of creating the informix user and group during a silent install with a response file? Thanks in advance.