Meaning of ':' in Qt directories

I'm trying to get acquainted with the Qt approach to directories.
In the "Text Object" example I see that the default file name is
":/files/heart.svg"
I made some tests under Win and Mac, searched the documentation, but still I'm not sure about the meaning of the ':' character.
Anyone can help?
Direct answers about the meaning of ':' as well as links to documentation about Qt implementation of directory structures (of different OS's) are appreciated.

It's the resource path, read here.