By each of those functions do you mean "TEXT", "PAGING", etc..? If so, here is what functions they provide.

"+SELECT" is the same as "PAGING" but when you hover over the album, artist, title, etc.. it automatically accepts the selection without pushing the enter command.

"PAGING" provides the functionality to move forward and backward in pages when the lists of whatever you are displaying are longer than can fit onto one screen with the familiar [..] unix type paging commands. For instance the top of each list will have a [..] on it and if you select that it will display the previous page of data. Likewise the bottom of each list will have a [..] and that will present you with the next page of data.

"CACHE", I believe, uses internal memory to read the data from the iPod and store the information into the Dension unit so it does not have to go back and forth reading to the iPod each time you ask for a new set of data.

"TEXT", I believe simply provides the actual textual information that is displayed on the unit.

"NO TEXT", Well I would guess this would disable the ability of the Dension product to deliver text to the PCM head unit. This option would be for head units incapable of displaying text.

It seams to me that these commands are somewhat heirarchical in that if you select "+SELECT" you get all the features of "TEXT", "CACHE", and "PAGE". I don't like the "+SELECT" feature because when I'm browsing a list and look up to see the road I don't necessarily want to automatically select that song, or artist, or album, etc.., therefore, I have my unit set to "PAGE".

Hope that helps and while I believe this information to be correct it is just from experimentation and I have not experimented much with "NO TEXT", "TEXT", and "CACHE" modes so hopefully I'm steering you in the wrong direction.