Any version 6 cards can/could be updated. That started in mid 2010.
All cards since then are version 6. Additionally since then all the cards for popular sonar/GPS brands are microSD and come with a SD adapter and USB card reader for updating with your computer.
Navionics Hotmaps Premium just has Navionics maps--Nautical Charts.
Navionics Hotmaps Platinum has Nautical Charts, 3D, Satellite Overlay and photos. PLUS it can have Sonar Charts downloaded to it when doing an update.
S5 is the South Region for 2009.
Version 5 and earlier was only annual editions with each year having more coverage than the previous years.
About version 4, Navionics lost the rights to publish map details they got from "other sources". Eversince they have been adding some of those details back as the do their own surveys or resurveys of waters. That includes roads, creek/river channels, submerged culverts/bridges.
That is where the Freshest Data Updates come into play. A new purchase includes a year of Freshest Data Updates.
The current maps can be viewed on the Navionics website Web App and that is what you get when you do a Freshest Data Update.
Once the year has expired, you can renew the Platinum card for another year for $99.
When the Premium expires, that cannot be renewed, but you can use it to activate the Navionics Update card $99 so the Update card becomes the 2GB version of Navionics+ with no maps. You choose what locations to download to the card from anywhere in the US and Canada. PLUS you can download the Sonar Charts map layer.
Additionally as long as your subscription is active, you can delete all on the card and reload what you want.
There is a discontinued Navionics+ 2GB card that some dealers may still have in stock.
The current Navionics+ is called PRELOADED and has all the maps for the US and Canada plus it can have Sonar Charts when updated.
It is a 16 GB card that can the renewed, and deleted then reloaded with just what you want. Some are doing that for units with slow processors.
Humminbird Helix 12 SI, 1198c SI, 1198c SI, ONIX 10 SI NT, 360, RC-1