Historical models: Which product implemented the CODASYL DBTG (network) data model?

Introduction / Context:
Before relational databases dominated, earlier models such as hierarchical and network (CODASYL DBTG) shaped the evolution of data management. Identifying which products mapped to these models is essential for understanding DBMS history.

Given Data / Assumptions:

• We compare well-known products: IDMS, DB2, dBase-II, R:base.
• Goal: pick the network model (CODASYL DBTG) implementation.

Concept / Approach:
The CODASYL DBTG model uses sets and owner–member relationships (network pointers). Commercial systems implemented this in the 1970s–1980s; CA-IDMS (originally Cullinet IDMS) is a canonical example of a CODASYL network DBMS.

Step-by-Step Solution:

Verification / Alternative check:
Documentation and historical references consistently classify IDMS as a network model DBMS aligned with CODASYL principles.

Why Other Options Are Wrong:
They correspond to relational or desktop file-oriented systems and not to the CODASYL DBTG network approach.

Common Pitfalls:
Confusing “early” relational systems (e.g., DB2) with earlier non-relational models.

Final Answer:
IDMS