COLLABORATIVE DEVELOPMENT OF LARGE - SCALE BIOMEDICAL ONTOLOGIES - Collaborative Computational Technologies for Biomedical Research - page 187

Proposal), status, and begin and end date. These search criteria can be com-
bined using the AND and OR logical operators.

12.2.2 Tracking Changes

Collaborative Protégé tracks all changes the authors make in the ontology.
The Changes tab presents a list of changes in chronological order. Figure 12.5
shows the Changes tab with some of the changes performed during the ICD-11
development process. Each change in the table has metadata associated with
it, including a human-readable description (e.g., “Added a new defi nition to
A17 Tuberculosis of nervous system”), an author (not shown in Fig. 12.5), a
date when the operation was performed, the entity on which the operation
was performed (e.g., the class A17 Tuberculosis of nervous system), and the
type of the change (e.g., Class created, Class deleted, Composite change, etc.).
The individual change records are stores as instances of the Change class
in the ChAO ontology. Each subclass of the Change class represents a different
type of change. Figure 12.2 shows some of the main subclasses of the Change
class. We use the type of changes to compute statistics about these changes,
such as the number of classes that have been moved from one branch of an
ontology to another one.
A Composite change is an operation that the user perceives as atomic but
which is composed of several other operations. For instance, retiring a class

Figure 12.5 The changes tab plug-in shows a structured list of changes in the ontology.
Each line in the table represents a change together with its metadata: type, author,
description, entity on which the change occurred, and the date.