I know this one lol
sl or sex linked is the way in which the color or trait was inherited. There is also recessive, and dominant.
sf or single factor means the bird is carrying a single copy of a mutation gene from the parents. DF or double factor would mean the bird was carrying two copies of the mutation gene. For example you will see this used when describing the color violet blue. There is sf violet blue and DF violet blue
I hope I explained that correctly
