[SMT-LIB] What does "c::main::1::IN!0 at 1#0" mean in a SMT-lib file?

[Zhoulai]

Hello, I come across this statement in a SMT-lib file:
(define-fun t () (_ FloatingPoint 8 24) |c::main::1::IN!0 at 1#0|)

Can anyone explains to me on the '|c::main::1::IN!0 at 1#0|' part? Thanks.

Zhoulai