B3: Category naming: letter "T" does not work.

[marsh]

The letter "T" cannot be used as category name.

[helmut]

The letter "T" cannot be used as category name.

Confirmed. But it's the lower case "T". Also other letters cannot be used (e.g. upper case "A") since these are interpreted as short cuts.
-> Confirmed

[marsh]

It now has T & A.
Fixed in ß-4.