It would depend on the how citations are made for the particular register in question. We can say at a particular location when referring to US legal code, for example:
Under the FLSA, employees in executive, administrative, and
professional positions, as well as employees in foreign areas, are
considered exempt. Rules governing exempt and nonexempt status for
federal employees are at 5 CFR Part 551.
Compensatory time off can also be approved for a federal wage system employee, as defined at 5 U.S.C. 5342(a)(2).
Some employees, mainly certain managers and supervisors, are exempt
from the FLSA but may receive overtime pay under Title 5, U.S. Code
("Title 5 overtime"). They are limited in overtime to either one and
one half times the hourly rate of a GS-10, step 1, or the hourly rate
of the employee's basic pay, whichever is greater, under 5 U.S.C.