Woking with multiple rails versions on same machine

If you have multiple rails versions installed like this -

rails (1.2.6, 1.2.0, 1.1.6)
Web-application framework with template engine, control-flow layer,
and ORM.

And you want to create 3 applications using 3 different versions of rails, then here is the command -

$ rails _<railsversion>_ <app name>

To create rails application using rails-1.2.0

$ rails _1.2.0_  r120

To create rails application using rails-1.2.6

$ rails _1.2.6_  r126

To create rails application using rails-1.1.6

$ rails _1.1.6_  r116

Is this documented anywhere?