[development] Upgrade system

[Gordon Heydon]

Hi,

Last night I converted E-Commerces old update system to the very cool
new one. However I did run over 1 issue.

When I am loading a fresh version of the schema, how do I tell the
system which revisions have already been loaded.

I know that the update system takes this from the system table, but I
couldn't even find where Drupal does this.

If anyone can enlighten me, I will be much appreciated.

Thanks in advance.
Gordon.