A TB earns 'black type' when it wins or is placed in a stakes race. If it is placed 2nd/3rd in a stakes race, then the horse's name appears in lower case, but bold in the pedigree. If it wins a stakes race, then the horses name appears as Capitals and bold in the pedigree. If it comes in 1st, 2nd, 3rd in a Group race (Mainly in Europe) or a Graded race (mainly Stateside) then the level of race is dipicted in the pedigree with a (G1), in bold, which indicates that the race was a Group/Grade One (highest level) contest - (G2) and (G3) follow suit.
If I wasn't so tired I'd look up some examples for you - sorry!