User's Custom properties name

Can you tell me all the custom properties names for the user... In API documentation, I can see only few properties.

{
    "prp":{
        "cfmt":<text>,        /* coordinates format: "0" - degrees and minutes, "1" - degrees */       
        "email":<text>,        /* user e-mail */
        "msc":<text>,        /* map position after launching: "0" - by default, "1" - saved */
        "poisrv":<text>,    /* render POIs on server */
        ...           
    }
}

Thanks in advance