Sheet - Default tab should be called default

[auniverseaway]

We started off with data, but this isn't great for multi-sheets. There's going to be some pain here for existing content.

I think we change this in UI, and whatever existing sheets are already called data, we leave as is so they do not break.

[auniverseaway]

I would also research what the behavior is in Excel when you go to multi-sheet.

[auniverseaway]

After doing a bit of digging, default won't work as all other tabs are then ignored.

[chrischrischris]

@auniverseaway Should we just call it sheet1 like in Excel?

[auniverseaway]

This is effectively done.