POSC Specifications
Version 3.0
Epicentre Modeling Methodology



This document defines the methodology that is to be used when creating a version of the Epicentre Data Model. The primary constraint on this methodology is that it must use the ISO EXPRESS language as subsetted and extended by POSC. A secondary constraint is that it must be capable of being accessed by an implementation of the POSC Data Access and Exchange Specification. This second constraint has influenced the choice of what subset of EXPRESS to utilize.

Epicentre is intended to be a logical model. In order to implement the model using an RDBMS it must be transformed into a data definition language (DDL), such as Standard Query Language (SQL) DDL. POSC refers to this process as projection. In order to use the DAE for access of the resultant physical data model, a linkage must be maintained between the logical entities and their physical representations in the database. This is necessary in order to have an unambiguous understanding of how the logical data model instances are mapped to physical instances. See the POSC Relational Implementation Methodology for a discussion of this process.


This document is intended for the following audience:


POSC has developed Epicentre through an open process of information exchange with the petroleum industry, its related service industries, other computing standards bodies and various regulatory bodies. The open process has provided a forum for interested parties to contribute ideas, requirements, and recommendations of solutions to meet the requirements. POSC has evaluated suggestions with careful deliberation and produced these specifications based on sound technical reasoning.

Normative References

The following contain provisions that, through reference in this document, constitute provisions of this specification.

EXPRESS Language Reference Manual, ISO International Standard 10303-11, Product Data Representation and Exchange - Part 11, TC184/SC4/WG5, March 1994.

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