Specify ID while creating/modifying account

[czaveri]

If I create a new account, can I specify it to have an ID, I want?

Can I modify an existing account's ID?

If no tools exist and I am willing to do it manually by updating the database, LDAP, etc. which are the places where I need to correct this? (so that the change of ID is seamless and without adverse effects)

Edit:
I just realized that perhaps it is an auto_increment value ...

Can I specify, then, the account name based upon which one would be the next ID?

Is there a Zimbra API or something that I can use to create / modify accounts?

[czaveri]

I always ask myself to search better but I never search enough...

This post satisfies my inquisitiveness.