There seem to be two different formats of Content IDs, a 4-digit format used to identify system updates, and a 7/8-digit format used for everything else.
4-digit / "Secure Content ID" format
Only used for SKSAs, where each update can have 3 different content IDs associated with it: a content ID to identify the update itself, and separate content IDs for the SA1 and SA2 parts included with it. (eg. SKSA 1106 contains SA1 1095 and SA2 1107)
With this format it seems the last 3 digits are used as the version number, with the first digit assumed to be the ID of the title (always 1).
Note that content IDs in this format can't be used by themselves to uniquely identify content, for example there are 3 different SA1s that all share the same 1095 content ID, but with differing content hashes.
Used for games, manuals and apps. Games and manuals always use the 7-digit form, while apps use 8-digits. The system used supports up to 100 versions of 100 titles in 100/1000 genres, and their respective manuals.
As an example of the format, Super Mario 64's content ID is 1101104:
- The first, second characters (1101104) define the genre.
- The third and fourth characters (1101104) actually identify the game, increasing by 1 with each new game in the genre.
- The fifth character (1101104) determines the type of content - 1 for a game, 9 for a manual, (and possibly 0 for an app). Other types of content were likely planned.
- The sixth and seventh characters (1101104) are thought to be the version of the content. There is some evidence supporting this hypothesis, yet there's no definite proof.
(for 8-digit IDs, remove the first digit and assume the genre is "100" or "200" for the format above to work)
Internally, the iQue Player converts the content IDs to hexadecimal (e.g. 0010cd30 for Super Mario 64) for storing .app, .rec and .sta files.
Cache storage on iQue@Home
On iQue@Home, the contents are stored in 2 levels of folders within the /cache folder depending on their first four digits:
The first two digits will be the first level directory, and the next two digits will be the second level directory.
- iQue Club 10000003 is stored at /cache/10/00
- Super Mario 64 1101104 is stored at /cache/11/01
- Newest SKSA Version 1106 is stored at /cache/11/06
When an item is being downloaded from the server, it would be temporarily stored using the same 2-level folder system, but within the /incoming folder. For instance, when downloading Super Mario 64, its cache is temporarily stored at /incoming/11/01/