What is preferred code?

I was searching for an example in the Sample Code Library and noticed that Rockwell Preferred Code samples are almost entirely faceplates. It seems that no other program in the library qualifies as "preferred code"

I wonder if there is a guideline or something to follow to write "preferred code"

Is there any written set of rules to follow that guarantees your code will be considered as "preferred code"?

Is it actually relevant that your code be considered as "preferred code"?

Any light?