Table of Contents

1. Introduction

2. Purpose
3. Format

3.1. Control frame 3.2. Table of Content (TOC) 3.3. Grey patches 3.4. Client descriptive files 3.5. Representation Information format description 3.6. Digital Preservation and How to Retrieve Data 3.7. Storage Medium description 3.8. Data Retrieval Technology 3.9. Generic Preservation Reel Structure (reel format) 3.10. Generic 4K Frame format description 3.11. Unboxing library / AFSLibrary description 3.12. Unboxing library source code / AFSLibrary 3.13. Plain Text ASCII encoded description 3.14. C99 language format specification 3.15. POSIXTAR source code 3.16. PDF/A-1 viewer source code 3.17. File format specifications and source code viewers

1. Introduction

The Representation Information is a section of the Archival File System (AFS)1, see figure 1.  The reference model for digital repositories OAIS (Open Archival Information System- ISO 14721:2012)2 defines the Representation Information as metadata that represents all the information needed for reading and understanding digital files in the future. In Piql, Representation Information is the metadata written in human readable format that provides information for decoding and reproducing the files in the future. This metadata contains the decoding open source code, the software description, descriptive documents of Piql technology, file format specifications descriptions and any customized information a client would want to add to improve understandability in the future.

This document explains the format and components of the Representation Information section. This information is written in human readable format.

                                       **Figure 1. Archival File System (Reel format)** 

1 Generic Preservation Reel Structure document, Piql 2 Reference Model for an open Archival Information System (OAIS) ISO14721:2012, https://public.ccsds.org/Publications/Archive/650x0m2.pdf/default.aspx

2. Purpose

The main objective of the Representation Information is to describe in human readable format how to recreate and interpret the digital content stored on a reel in case the technology and competence are not available sometime in the future.  Piql’s digital preservation process is not only focused on preserving the bits of information but also in preserving the file accessibility plus ensuring that it is understandable and readable, regardless of the evolving technologies.

3. Format

The Representation Information is divided into fixed files; which always are present on the film (e.g. decoding software source code), and changeable files; that varies according to the nature of the content (e.g. file formats) or due to clients’ requirements (e.g. Information required by law regulations, copyright statements).  Following are the sections of the Representation Information in the order as they are stored on the film:

**Optional: Client reel head files are repeated at the end of the reel. *** File formats printing rights must be acquired by individual client