What it asks for. The organisation must apply defined processing conditions to specific categories of personally identifiable information, such as particularly sensitive types.
In practice. In NIST this covers categories such as Social Security numbers and First Amendment information. For European readers the closest equivalent is the stricter treatment of special category data and criminal offence data under GDPR Articles 9 and 10. Good practice is identifying where such data is held, limiting access, applying stronger protection and documenting the conditions that permit processing. Auditors look for data mapping, access restrictions and documented justifications.
Common gaps. Sensitive categories are often held in places nobody mapped, such as free-text fields and email. Access to these data sets is frequently broader than needed.