1. Introduction

In order to use a variety of SGML tools in a variety of computer environments, there are two different but related problems to solve:

1. that of interpreting external identifiers in entity declarations so that an SGML document can be processed by different vendors' tools on a single computer system, and

2. that of moving SGML documents to different computers in a way that preserves the association of external identifiers in entity declarations with the correct files or other storage objects.

There are many important issues involved and a complete solution—possibly including work within the standards community—is beyond the current scope. However, the OASIS membership agrees at this time upon a set of conventions that addresses a useful subset of the complete problem.

The short term solution for issue A defines an entity catalog that handles the simple cases of mapping an external entity's public identifier and/or entity name to a file name, URL, or other storage object identifier. This solution allows for a probably system-dependent (at least in the case of file names) but application-independent catalog. Though it does not handle all issues that a combination of a complete entity manager and storage manager addresses, it simplifies use of multiple products in a great majority of cases and can in some cases (e.g., with URLs) provide internet-wide, system-independent resolution of public identifiers.

While there are various interchange strategies already defined—including the SGML Document Interchange Format (SDIF) defined in ISO 9069—none are currently widely used or supported by enough readily accessible implementations. This resolution addresses issue B by defining a simple interchange packaging scheme using an interchange catalog to associate a public identifier with each interchanged file.