custom poi tones

greetings ,
i hope you can help me in that matter.
i have a nuvi 50 and i have many files for my custom poi
and when i go to proximity points to choose alert
i find all my files will have the same alert
so i want each poi file to have a its alert and some poi to not have any alert
so
how can i do that
if any one know please help me in that matter

waiting for your help
bye.

When you create .gpi files with Garmin POI-loader, you can make POI with custom alert souns and custom symbols. The files for coordinates (gpx or csv), symbol (bmp) and sound (wav or mp3) must have the same name except the file extension, e.g. mypoi.gpx, mypoi.bmp, mypoi.wav.

can you give me an example
thanks