Well,I'm no expert-but we do cook some briskets.
The "packer" is what the meat packer sends them in the cryovac,and contains the point and flat segments.
Depending on your usage for the meat,i.e. comps,vending,catering might determine what/how you trim-before you cook.
Some volume cooks will leave them untrimmed,until completely cooked.
Much of the fat will melt away and the remaining can be scraped off, easily.
If you have a specific need,ask and someone will jump in.
Hope this helps a little.