This SGML Open Technical Memorandum consists of a recommendation for an update to the CALS table model DTD model that will be submitted to the appropriate CALS authority with the expectation that it will be accepted as the next revision of the official CALS table model and that a Formal Public Identifier will be assigned to facilitate referencing of this model.
Note that the set of element and attribute declarations in the markup declaration module section of this document partially defines the CALS table model. However, the model is not well-defined without the accompanying natural language description of the semantics (meanings) of these various elements, attributes, and attribute values. The semantic writeup, in the section following that containing the markup declaration module, must be used in conjunction with the element and attribute declarations.
This SGML Open Technical Resolution defines an Exchange subset of the full CALS table model DTD described in SGML Open Technical Memorandum TM 9502:1995. This Exchange subset has been chosen as being a useful subset of the complete CALS table model such that, if an application's tables are tagged according to this subset, there is a high probability that the table will be interoperable among the great majority of SGML Open vendor products. See also the SGML Open Technical Research Paper TRP 9501:1995 on Table Interoperability: Issues for the CALS table model.
Note that the set of element and attribute declarations in the markup declaration module section of this document partially defines the Exchange table model. However, the model is not well-defined without the accompanying natural language description of the semantics (meanings) of these various elements, attributes, and attribute values. The semantic writeup, in the section following that containing the markup declaration module, must be used in conjunction with the element and attribute declarations.
HyTime (Hypermedia/Time-based Structuring Language) is a markup language that is an application of SGML. HyTime defines a set of hypertext-oriented element types that, in effect, supplement SGML and allow SGML document authors to build hypertext and multimedia presentations in a standardized way.
The Standard Generalized Markup Language (SGML; ISO 8879:1986) is a standard for defining generalized markup languages for documents.
To help address the existing interoperability issues when using tabular material (“tables”) in SGML implementations, SGML Open's Technical Committee formed a Table Interchange subcommittee to research these issues.
Because the CALS table model has proliferated widely, it was chosen as the initial starting point. Although it has evolved to the point of a de facto standard, the specification leaves a large number of semantics open to interpretation which in turn has made interoperability difficult to achieve. As its first major task, the Committee therefore set out to identify and document ambiguities in the CALS table model specifications, identify and document related interoperability issues between SGML Open vendor products, and lay the groundwork for developing a proposed clarification of the standard that will minimize ambiguity and maximize interoperability.
This paper summarizes the results of this initial work, identifies the sources of current interoperability issues for the CALS model, and summarizes the most common set of practices currently followed by SGML Open vendors.