Data architecture provides the most comprehensive information for understanding a transaction audit trail. It defines the structure, relationships, and management of all data within the application, including how transaction data is captured, stored, and linked to user activities, timestamps, and other relevant events. This holistic blueprint allows an IS auditor to understand the entire lifecycle of a transaction's data, which is the essence of an audit trail, rather than just viewing a single process or file structure in isolation.

A. System/process flowchart: This illustrates the flow of operations but lacks the specific detail about the data elements that are captured and stored in the audit trail.

B. File layouts: This is too specific, as it only describes the structure of flat files. Modern online applications typically use databases, and this option would not describe the relational structure.

D. Source code documentation: This provides a highly granular, implementation-level view. It is inefficient for an auditor to review code to understand the overall audit trail design and data relationships.

1. ISACA

CISA Review Manual

27th Edition

2019. Domain 3: Information Systems Acquisition

Development

and Implementation

Section 3.3.5 Data Files

states the importance of understanding the "application system’s data structure and file organization" to test application controls. Data architecture documentation provides this comprehensive view

which is essential for evaluating the completeness and accuracy of an audit trail.

2. Spewak

S. H.

& Hill

S. C. (1992). Enterprise Architecture Planning: Developing a Blueprint for Data

Applications

and Technology. While a foundational text

its principles are core to IS audit. Chapter 3

"Data Architecture

" explains that this architecture defines the major kinds and types of data and their interrelationships. An audit trail is a kind of data

and its relationship to transaction data is defined within the data architecture.

3. Zachman

J. A. (1987). A framework for information systems architecture. IBM Systems Journal

26(3)

276-292. The Zachman Framework

a seminal work in enterprise architecture

defines the "Data" column (the "What") as a core component of understanding a system. An audit trail is fundamentally about data—what happened

what data was affected

etc. The data architecture provides this perspective

detailing the entity-relationship models necessary to trace transactions. (DOI: 10.1147/sj.263.0276)