Why is `.U` in info.txt?

[Makonede]

Just under .u in info.txt, I found a new "command:" .U. All it says is push a with . It seems to have been added to info.txt at the same time as ÅÏ, but never has it appeared in the source code. My question is, why is this here? Why is a non-existent command in info.txt?

[Adriandmen]

Very mysterious. I have been looking through the commits, the current lexer, and the legacy version as well. It seems that the .U command was never implemented at all.

I have no idea why it is in the documentation. The most likely thing that I could imagine what happened is that I had some idea for it, implemented it, and promptly removed it.

[Makonede]

In fact, from what I can tell, .U only ever appears in info.txt and no other documentation. Did a search and looked through the wiki, nothing.