SNP genotyping is the measurement of genetic variations of single nucleotide polymorphisms (SNPs) between members of a species. It is a form of genotyping, which is the measurement of more general genetic variation.
On most plays, the center will snap the ball directly into the quarterback's hands. In a shotgun formation, the center snaps the ball to the quarterback lined up several yards behind him.
Answer: For the offense, you must have 7 or more players on the line at the snap. If not, it's an illegal formation, 5 yard penalty. The defense, on the other hand, is not required to have any players on the line or to be in any particular formation.