So, what do all those letters mean?

CH: Champion, either American or Canadian
GCH: Grand Champion
SDHF: Show Dog Hall of Fame
JAM: Judge's Award of Merit
BIS: Best in Show
BISS: Best in Show Speciality
BOSS: Best of Opposite in Show Specialty
Winner's Bitch, Winner's Dog
BOW: Best of Winners
RWB/RWD: Reserve Winner's Bitch, Reserve Winner's Dog
CD: Companion Dog, obedience title
MX: Master Excellent, agility title
MXJ: Master Excellent Jumper, agility title
AX: Agility Excellent
AXJ: Agility Excellent Jumper
OA: Open Agility
OAJ: Open Agility Jumper
NA: Novice Agility
NAJ: Novice Agility Jumper
MXP: Master Agility Excellent Preferred Standard
MJP: Master Agility Excellent Preferred Jumpers
AXP: Agility Excellent Preferred Standard
AJP: Agility Excellent Preferred Jumpers
OAP: Open Agility Preferred Standard
OJP: Open Agility Preferred Jumpers
NAP: Novice Agility Preferred Standard
NJP: Novice Agility Preferred Jumpers
NAC: Novice Agility Certificate (NADAC Title, V=Veteran)
NJC: Novice Jumpers Certificate (NADAC Title, V=Veteran)
TD: Tracking Dog
MH, SH, JH: Master, Senior, Junior Hunter titles
CGC: Canine Good Citizen
TDI: Therapy Dog International designation
SAR: Search & Rescue