Overlays Capture Architecture

Official OCA resources


Content driven

Immutable objects backed by Self-Addressing Identifiers cryptographically bound to the content, assure about security and portability

Simplified data pooling

Decoupling can occur at any time as overlays are linked objects. With all colouration definitions stored in the overlays, combining data from related sources becomes seamless.

Stable capture base

All extension and colouration definitions are applied in the overlays, enabling issuers to edit one or more of the linked objects to create simple updates rather than reissue capture bases on an ongoing basis.

Flagged attributes

Issuers can flag attributes in the capture base that could potentially unblind the identity of a governing entity


A separate linked data object captures character set encoding definitions. Thus, a single report definition can contain different attribute forms for different languages.

Credential presentation

Support for flexible credential presentation, in secure and controled way


Cryptographically linked objects allow for high reusability, nesting, and referencing already existing capture base increasing interoperability of created objects.

Data validation

Ensure captured data records are OCA bundle schema compliant

Data transformation

Datasets transformation using tranformation overlays