First of all let me tell you that I'm really in awe by the momentum of the LatD! And I can certainly expand the perimeter of the units allowed to include the Dark Mechanicus units and the Eyerine Cult! It's fitting and fluffy!
Each participant is called to make at least one and up to a maximum of five (5) vows pledging to paint legal units from the Codex or any other army list associated with his/her Faction of choice. Also each vow should not exceed the limit of 3,000 pts. For more details regarding the content of the vow, please see “Legal Entries” section below.
That's from the etl v link in the captains sig...
also, from the faq bit:
Q: I pledge for Chaos. Can I use units form all associated Codices and FW lists? And can I do it in the same vow?
A: Yes! Chaos has a single Strategium and as such any unit from any associated list is ETL-legal. Even within the same vow!
Dunno if that counts or not, I'm quite out of date with terminology here.
Sorry spafe, you're quoting ETL V rules there... The rules for ETL VI (that I had not yet linked in my sig) state otherwise... I now will proceed to add the ETL VI rules in my sig for easy reference!