The construction confined-space standard was written for sites with many employers, so its first section is mostly about who owes what to whom.
Identification. Before it begins work at a worksite, each employer must ensure that a competent person identifies all confined spaces in which one or more of the employees it directs may work, and identifies each space that is a permit space, through consideration and evaluation of the elements of that space, including testing as necessary (29 CFR 1926.1203(a)). Note the subject: each employer, for its employees. A subcontractor cannot assume the general contractor's survey covers it.
Notification. If the workplace contains permit spaces, the employer who identifies or is notified of one must inform exposed employees — by posting danger signs or another equally effective means — and must inform, in a timely manner and in a manner other than posting, its employees' authorized representatives and the controlling contractor (29 CFR 1926.1203(b)).
Keeping people out, or getting them in properly. An employer that has not authorized its employees to enter a permit space must take effective measures to prevent entry (29 CFR 1926.1203(c)). An employer that decides its employees will enter must have a written permit space program complying with 1926.1204, implemented at the construction site and available for inspection by employees and their representatives before and during entry (29 CFR 1926.1203(d)). Alternate procedures for spaces whose only hazard is atmospheric and controllable by forced-air ventilation exist, under the conditions in paragraph (e) (29 CFR 1926.1203(e)).
If a reviewer asks one question about a construction permit space, it is usually "who was the competent person who evaluated it, and when?" The standard puts that step first for a reason.