Can a Lua implementation use 63-bit integers or even "big integers"?

["Soni \"They/Them\" L." <fakedme@...>]

A lot of code written for Lua 5.3+ assumes integers are 64-bit,
including stuff that involves UUIDs. However, would it still be in spec
to have 63-bit integers, or even "big integers" (if capped to some
length to satisfy math.maxinteger/math.mininteger)?