nsIPassword in Firefox 1.5

 the name of the host corresponding to the login being saved

 The form of the host depends on how the nsIPassword object was created

 - if it was created as a result of submitting a form to a site, then the
   host is the url of the site, as obtained from a call to GetSpec

 - if it was created as a result of another app (e.g., mailnews) calling a
   prompt routine such at PromptUsernameAndPassword, then the host is whatever
   arbitrary string the app decided to pass in.

 Whatever form it is in, it will be used by the password manager to uniquely
 identify the login realm, so that "newsserver:119" is not the same thing as
 "newsserver".

 the password portion of the login

 the user name portion of the login