Before the Windows CE product was released we had an internal set of tools known as the Oem Adaptation Kit also known as the OAK - an OAK of course is a type of tree.
The initial releases of Windows CE were therefore named after trees, as follows.
Interestingly, there was a second team within the Windows CE group that worked on the tools, I guess you could consider tools to be something that makes a job easier, or cuts the job down to size - therefore the tools releases were named after things that cut down trees - as follows...
For Windows CE 4.0 the original plan was to call the O/S DougFir (DouglasFir), the thing that cuts down DougFir trees was going to be Dozer (BullDozer) - interestingly, at Windows CE 4.0 the o/s team and tools teams merged together to form a new, combined team - the codenames for the operating system and tools also changed at this time from trees/tools to <drumroll>Whiskeys</drumroll> - so the codenames for Windows CE 4.0 onwards are as follows.
*originally posted on Mike Hall's Weblog