Varieties of comma-free codes

New varieties of comma-free codes CFC of length 3 on the 4-letter alphabet are defined and analysed: self-complementary comma-free codes (CCFC), C3C3 comma-free codes (C3C3CFC), C3C3 self-complementary comma-free codes (C3C3CCFC), self-complementary maximal comma-free codes (CMCFC), C3C3 maximal comma-free codes (C3C3MCFC) and C3C3 self-complementary maximal comma-free codes (C3C3CMCFC). New properties with words of length 3, 4, 5 and 6 in comma-free codes are used for the determination of growth functions in the studied code varieties.