bcquality/microsoft/knowledge/privacy/data-classification-required-on-pii-fields.md

bc-version	domain	keywords	technologies	countries	application-area
all	privacy	data-classification pii gdpr customer-content table-field under-classified	al	w1	all

DataClassification is required on table fields containing sensitive data

Description

DataClassification is the AL property that tells the platform what kind of data a table field stores so that telemetry, GDPR data-subject requests, and the platform's audit surfaces can treat it correctly. It is required on any field that holds personal, customer, or organization data. When the property is omitted, AL applies ToBeClassified — a placeholder meaning "not yet reviewed", not a safe default. Leaving a field that actually holds PII (an email address, a customer name, an employee code) as ToBeClassified, or setting it to SystemMetadata ("no user or customer data") to silence the requirement, are both under-classifications and privacy bugs, even though the code still compiles.

Best Practice

Set DataClassification to the value that matches the data the field actually stores. A Customer."E-Mail"-style field is CustomerContent (data belonging to the tenant's customers); a personal identifier such as an employee number or user ID is EndUserIdentifiableInformation or EndUserPseudonymousIdentifiers depending on whether it is directly identifying. A field that identifies an organization rather than a person — a company registration or VAT registration number — is OrganizationIdentifiableInformation, and a financial account identifier such as a bank account number or IBAN is AccountData. Choose the classification at field definition time — fixing it later is a schema change.

See sample: data-classification-required-on-pii-fields.good.al.

Anti Pattern

Declaring a field that stores PII with DataClassification = SystemMetadata to silence the compiler warning. The field compiles but the platform now treats customer data as system metadata in telemetry, GDPR exports and admin reports.

See sample: data-classification-required-on-pii-fields.bad.al.