[build number].[revision number].[lab].[YYMMDD-hhmm]
or for private builds
* [build number].[revision number].[lab]([name]).[YYMMDD-hhmm]
* [build number].[revision number].private/[lab]([name]).[YYMMDD-hhmm] (exclusively pre-reset Vista)

Known labs list (with description):

----------------------------------------------
| Lab01 | Kernel                             |
| Lab02 | Networking                         |
| Lab03 | Server                             |
| Lab04 | Terminal Services                  |
| Lab05 | Main, I believe                    |
| Lab06 | User interface                     |
| Lab07 | Internet Information Services/COM+ |
----------------------------------------------
idx01-07 also exist and are mostly TAP/OEM recompilations, sometimes being public. Same lab descriptions I assume.



Might be helpful to look at https://ultradefinitive-build-list.fandom.com/wiki/Home for ideas