ESET product modules have two types of updates, Level updates and Nano updates. They differ in time range. There are 3 Level Updates - Level 0 (L0), Level 1 (L1) and Level 2 (L2). There are 20 Nano updates, from Nano 1 to Nano 20.
Nano updates represent the number of updates from the very last time of latest update, meaning, Nano 1 represents the very last update, Nano 20 represents the last 20 updates altogether. Upon next available update, all Nano updates are regenerated.
A module is updated with just one out of all Nano updates available. The number of Nano updates issued per specific module might differ from module to module and within the time.
Level updates represent the number of updates from the release date of particular module. L0 includes several updates from the time the particular module was released. L1 includes some subsequent updates and L2 the remaining updates, including all 20 Nano updates.
Once L2 approaches the size of L1, then updates included by L2 are drained into L1. Once L1 becomes as large as L0, then updates included by L1 are moved to L0.
L2 is gradually filled by older Nano updates, meaning, content of Nano 20 is moved to L2 when all Nano updates are regenerated upon a new available update.
After a fresh new installation of a product, the product is in its basic state and receives the essential Level updates:
[IMAGE - Level Updates + labels]
If a product is updated on regular bases, but would be offline for a few days, and after connecting to the update server the update Nano 3 update is identified as the missing one, then it would be applied:
[IMAGE - Applying Nano Update + labels]
An example of update files of a 32-bit engine module