Rename time dimension with YTD still available

[GeorgeDuckett]

I need to rename the months in the time dimension, but also need to have a YTD item too. I see there's an Idea submitted to enable renaming, however that has not been done at time of writing.

I understand to work around this limitation I can create a custom Time list with the desired display names and a lookup module to go from my custom list back to Time, however I'm unclear on how to get map the YTD figures. I have FINDITEM(Time, CODE(ITEM(Month List))) in my PROP Custom Time module, but that doesn't produce anything for the Time's YTD item, presumably because YTD isn't a month. When I try and change the formula's Summary method to formula it fails with this error:

I really don't want to go down the logic of replicating YTD logic (having a flag for the YTD item in my custom time dimensions then doing IF IsYTD THEN .... ELSE etc. as that would make the formulas (and there are many) vastly more complex, and with different summary methods needing replicating it'd just get very messy very fast.

So, stepping back a bit, how can I change the display names of the months, but still have YTD able to be looked up from the standard time dimension?

[GeorgeDuckett · Accepted solution]

Best I've come up with so far is IF PROP Month List.IsYTD THEN SourceData[SELECT:Time.YTD] ELSE SourceData[LOOKUP:PROP Month List.Time Month], but this isn't ideal as often 'SourceData' could be a more complex formula rather than just a single line item (and I can't create an intermediary line item due to model size constraints).