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Welcome to the Units of Functionality Repository! This repository contains all of the information in the Units of Functionality clause (4.1) for STEP application protocols of International Standard (IS), Final Draft International Standard (FDIS), or Draft International Standard (DIS) status. The following information is available:

The repository also includes the following implicit information, derivable from clause 4.1 but not stated explicitly:

Using the forms below, you may browse the repository or search for a particular unit of functionality or application object.

To learn more about the role played by units of functionality in the STEP application protocol development process, look at the Guidelines for the development and approval of STEP application protocols. This document is in PDF format and may be read using Adobe's free Acrobat Reader software. Acrobat Reader may also be used to view PDF graphics in the UoF Repository.

Please contact the NIST Application Protocol Development Environment project team if you have any feedback or comments regarding this service.

About the UoF Repository

The UoF Repository is generated from digital ASCII versions of STEP application protocol documents as follows:

  1. The ASCII files are run through a filter program (written in perl) in order to extract the UoF clause (4.1) and mark it up in SGML using the STEP DTDs.
  2. Markup is added manually using a text editor for elements such as notes, figures, and examples within some of the UoF definitions. This step does not take very long because most UoF definitions require no embedded markup.
  3. An SGML database is created for the resulting SGML documents using third party software that creates indices for rapid retrieval and provides a query processor.

Because most of the above procedure is automated (and the non-automated part is small), it is easy to re-generate the UoF Repository as needed when new application protocols become available or when existing application protocols advance in status.

The UoF Repository uses the same web gateway framework that was developed for NIST's Application Protocol Information Base, documented in the following paper:

Joshua Lubell, The Application Protocol Information Base World Wide Web Gateway, 1997 ASME Design Engineering and Technical Conferences, September 14-17, 1997, Sacramento, California. Available in Postscript and PDF formats. Note: this paper supersedes NISTIR 5868.

A few new access functions were implemented to support UoFs, and additional CGI scripts were written to generate HTML pages from the query results.

In case you are wondering about the strange logo for the UoF Repository, it is supposed to be an "unidentified flying object" or "UFO" (an anagram of "UoF"). Suggestions for a new logo are welcome.

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Go to the NIST Application Protocol Development Environment home page.

Written by Joshua Lubell

Last modified May 17, 1999
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