I can confirm that. On the TI-83, many of the TI-BASIC tokens contained lowercase characters which couldn't be typed at all - you could only type uppercase letters on the keyboard. (There were a few lowercase letters available as tokens for special purposes, but it wasn't a full set.)
Interestingly, you could print tokens in strings - e.g. you could Disp "Disp ".
Interestingly, you could print tokens in strings - e.g. you could Disp "Disp ".