This loads the requested subframe of the specified page and makes it the current frame.
If you do not wish to specify a particular subframe to load (i.e. you know the chosen page only contains one frame), then use selectframe() to load the first found.
If the frame cannot be loaded for any reason, the current frame number will be set to 0. Script processing will continue. You should check the status to see if the frame was reloaded from the cache or not.