Compressed Custom IDs Format
In order to save storage and cookie size, the CMP will store the consent information in a propriatary format. This format is based on the bit-encoding logic of the IAB TCF Consent String or tcString (see https://github.com/InteractiveAdvertisingBureau/GDPR-Transparency-and-Consent-Framework ) but uses a different field order.
Note: In order to distinguish the Compressed Custom IDs Format from "normal" Consent Strings or tcStrings, the encoded string will alway start with a lowercase a.
Version 1
A Compressed Custom IDs string of version 1 will use the following field order:
| Field | Data Type | Description |
| Version | Int (6 bit) | Version of the string format. Should be 1. |
| Created | Date (36 bit) | Date when the string was created/changed. |
| User choice | Bool (1 bit) | 1= A user choice exists (user clicked on accept/reject/save) 0=The string is based on indirect behavior (CMP was shown, legitimate interest is established but user did not yet choose) |
| Purposes range length | Int (12 bit) | Amount of items in the following range field. |
| Purposes allowed | Range | Range of custom purpose IDs that are allowed |
| Systemvendors range length | Int (12 bit) | Amount of items in the following range field. |
| Systemvendors allowed | Range | Range of system vendor IDs that are allowed |
| Customvendors range length | Int (12 bit) | Amount of items in the following range field. |
| Customvendors allowed | Range | Range of custom vendor IDs that are allowed |
Reading range fields
When reading a range field, please follow these steps:
- Get range length (12 bit integer)
- Read first bit
- if first bit is 0, read two 16 bit integer as start-ID and end-ID of the range item
- if first bit is 1, read one 16 bit integer as single ID item
- Perform steps 2 - 4 for each range item (see range length)
Please note that range items with start-ID and end-ID mean, that all IDs within the two IDs are allowed (including start-ID and end-ID). E.g. a range item with start-ID 3 and end-ID 6 mean that IDs 3, 4, 5 and 6 are allowed.
