Are role values case sensitive?

Hi all,

Hope you are doing good. I would like to understand whether the ARIA role
values are case insensitive or case sensitive.  For example, if I put
either role=”LINK”(all the upper case letters) or role=”LiNk”(mixed case)
or role=”link”(lower case) then does it really matter? the reason for
asking this question is that I found strange results while I am doing this
particular study. During my study, the except NVDA FF and JAWS FF, no other
combination(NVDA chrome, JAWS FF, JAWS chrome) really concerns the upper
case/lower case of the role values. To put it simpler, except firefox
combinations(JAWS FF and NVDA FF), other combinations(JAWS chrome, JAWS IE,
NVDA chrome, NVDA IE) identifies the link as link irrespective of the
lower/upper/mixed case. In addition, how about eh case sensitivity of the
strings that we pass in the ARIA states/properties(ex: aria-expanded)

Could you please clarify my queries and do needful?

Thank you.