Okay-- PTI is a number that is a combination of both appraisal scores and milk test info.
The higher the number, the better chance you have of making improvements.
In the 2:1 ratio, production is weighted over type. 1:2 is type over production. If I want to add a lot of type to my program, I look for animals with a high 1:2 number. If I am looking to add milk, I look at the 2:1 numbers. Optimally, both numbers are high.
ETA is what you HOPE a buck will pass on, based on his sire and dam's PTI numbers. The higher the number, the greater chance for excellent offspring.