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Apache UIMA v1.4 and later support the proposed UIMA standard type-system language (i.e., Ecore). This ambiguity does not arise for type systems developed directly in Ecore
Type Definitions for Sofas
(See Section 5.3.3)
The UIMA Spec does not define Sofa as a type in the type system. Instead, conceptually any slot on any object in the CAS could be a subject of analysis.
To implement this, the UIMA Spec defines the type SofaReference. An Annotation's sofa feature points to an instance of type SofaReference. There are two subtypes: A LocalSofaReference is a reference to a slot of another object in the CAS (it has two fields - an object reference and a string slot name). A RemoteSofaReference is a URI to content that is not contained in the CAS.
Regional References for Annotations
(See section 5.3.4.1)
The UIMA spec suggests, but does not mandate, the use of an extensible RegionalReference type. For example subtypes might be TextRegionalReference and AudioRegionalReference. An annotation type such as PersonAnnotation could refer to either kind of regional reference. See the spec for a detailed discussion of the pros and cons of this approach.
Apache UIMA does not implement a separate RegionalReference type. Instead, for text annotations Apache UIMA defines a type named uima.tcas.Annotation that contains the features begin and end. These are intended to represents off-sets into the text string specified by the annotation's sofa feature. The type uima.tcas.Annotation, however, is not extensible to non-text artifacts. Furthermore, the begin and end features are UTF 16 code units which is not convenient for anyone using UTF-8 for example.
CAS Views
(See Section 5.3.4.3)
UIMA Spec Definition of a View: A View is a named collection of objects in a CAS. In general a view can represent any subset of the objects in the CAS for any purpose. It is intended however that Views represent different perspectives of the artifact represented by the CAS. Each View is intended to partition the artifact metadata to capture a specific perspective.
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