Numbering Exceptions

[HLin NC]

On 4th down or a try, under the numbering exception, once the player not numbered 50-79 takes the position of a player normally numbered 50-79 between the ends, he is ineligible, so even though they shift into a formation that makes them an end, they remain ineligible based on the initial positioning.
In your diagram, both 18 and 45 entered under the numbering exception . Your formation is perilously close to what the dreaded A-11 was trying to create. Under the rule, B and the officials are not tasked with determining who is eligible, they are both ineligible based on their initial positioning.

A player in the game under this exception must assume an initial position on his line of scrimmage between the ends and he remains an ineligible forward-pass receiver during that down unless the pass is touched by B (7-5-6b).

On downs 1-3, if A shifts or sets into a scrimmage kick formation, only the snapper may avail himself of the numbering exception and he must line up between the ends.