DCPS employs several mechanisms to bolster the security
situation. First is the forced atomicity of shot tree creation.
Historically, during testing, a user would create a new test shot
manually using a numerical series outside normal operations.
This has undefined behavior, however, when two users try
to use the same number. Different projects have developed
different methods to address the issue, including assigning
number ranges to specific people. However, no scheme stops
an accidental typographical error from destroying someone
else’s data. Therefore, NSTX-U instead has a scheme by which
a user can atomically request a new test shot, and have that
number atomically transferred to the test program without user
interaction. The atomic nature of the request prevents any two
users from receiving the same number