Web of trust and signature types? (sig1, sig2, etc)

Question

I have read about The OpenPGP trust model but I don't see any mention of the specific signature types. Are all signature types (sig0 - sig3) treated the same by tools such as gpg or the PGP Pathfinder?

Answer 1

Jens has answered this quite well. Basically, the signature levels are defined in the man page under --ask-cert-level and --default-cert-level. sig refers to cert level 0, which "means you make no particular claims as to how carefully you verified the key." This is the default when signing a key. They run up through levels 1 and 2, to the highest level, sig 3, which "means you did extensive verification of the key."