Entity attributes in the UK federation
The UK federation supports a small number of Entity Attributes in metadata.
Technical definitions of Entity Attributes and Entity Categories
Entity Attributes in SAML metadata are defined in SAML V2.0 Metadata Extension for EntityAttributes Version 1.0
Entity Categories are a type of Entity Attribute, and are defined in RFC 8409: The Entity Category Security Assertion Markup Language (SAML) Attribute Types. The RFC also defines Entity Category Support.
REFEDS Research and Scholarship
SPs specifically for research and scholarly collaboration can request personal data to facilitate collaboration.
GÉANT Data Protection Code of Conduct for SPs in the EU/EEA
A Code of Conduct around SP's behaviour with attributes
An assurance certification for entities which have a security incident response process.