Gurps hammer job table

[HolyChicken]

Hey

New to the forum, and kinda new to GURPS.

We are going to play a game tomorrow, and we just rolled the characters using the rules gurpshammer 2.0 rules

There is a job table in there, and i don't know what many critical failures mean, like: 4d,C and -1i

Anyone know what these stand for?

Thanks