The profile parameter has been designed to make checking in easier AND more secure. Rather than making the user/client specify all check-in related arguments (database, host, username, password, system and model), you just specify a profile name. This profile name must match a profile that has been setup for this repository duing the setup process. This means that if a database has been added to the profile list, users don't actually need to know anything about the database, just this profile name, and they don't have to supply such sensitive information over the web. Profiles are made during the setup process using the 'loginXMLs' tag. Also, ANY valid maxdQL argument can be placed in a profile, not just login details, so they can be used as a standard set of arguments for any task. Some profiles require a password, specified using the ppass argument. You normally implicitly choose the default database when you do not provide a profile argument, but in some situations it is necessary to provide an argument (e.g., when using the can of queries). To do this, you can use "DEFAULT" to access the default database.