This story is copied from a set of six case studies and tells about the rescue of the personal files database after “Die Wende” and the re-unification of East and West Germany.

Archive East Germany’s “Kaderdatenspeicher”
Purpose Personal files database of East Germany’s party functionaries Institution in charge German Federal Archives (Bundesarchiv)
Contents
The Kaderdatenspeicher contains personal data on 331,980 staff members (in 1989) of all former East German government agencies, excluding those of the Ministry of State Security, the Ministry for National Defense, and the Ministry of the Interior.
Technologies used
In general, and also in the case of the Kaderdatenspeicher, East German computer centers used mainframe systems for the processing of large data compilations. The data holdings usually had hierarchical file structures that were not very complicated. The hardware and software used were copies of and variations on Western models, naturally with different names. For instance, the socalled ESER-mainframe systems in East Germany were copies of widespread mainframes. As storage media, primarily 9-track tapes were used. Many of them had only a density of 800 bpi. Owing to production problems, these tapes bearing the East German trade marks ORWO or PYRAL proved to be in very poor condition. Glue and abrasion had to be removed from the tapes
before they could be read. Sometimes, layers of the tape separated after the first reading because of insufficient binder.
The labeling of the tapes followed the international standards, with hardly any variation. Similar to Western mainframe applications, EBCDIC was used as code. The Russian code DKOI (in the former GDR also called “ESER-Code”), which in translation means Binary Code for Information Interchange, could also be found in East German data files. DKOI is very similar to EBCDIC and is basically an enlargement of EBCDIC with a few variations.
Relevance of the archive
The files of the Kaderdatenspeicher not only provide insight into the political and professional career of officials, but they also contain information on their parents. There were several copies of the Kaderdatenspeicher, of which the only one that still exists is the one acquired by the Federal Archives. At least in one case, there is sufficient evidence that one copy of the Kaderdatenspeicher had been deliberately deleted shortly before the German unification in order to protect cadre members. The considerable value of this holding provided an incentive for the Federal Archives to invest quite heavily into the reconstruction of its documentation.
What happened to it?
In October 1990, after 45 years of separation and different institutional traditions, the former East German Central State Archives were merged with the West German Federal Archives. When suddenly former East German government agencies and institutions were closed down, not only their paper records, but also a considerable number of machine-readable data holdings had to be secured or rescued from possible destruction. Very often, however, as in the case of the Kaderdatenspeicher, the documentation of these electronic records proved to be incomplete or even totally missing, therefore different approaches had to be taken to identify and verify data file structures and to reconstruct missing documentation.
After first copying the tapes of the Kaderdatenspeicher, the volume labels, the headers, and the first blocks of data of each file were printed out. The volume labels and headers followed widespread schemes, so it was easy to comprehend them. From these data, information on the content of each tape and an initial idea of the different generations and applications of the Kaderdatenspeicher could be obtained. However, one typical problem already became apparent at this early stage. In the few lines of the volume label and headers, three different ways were used to express the date. Furthermore, the datasets of the Kaderdatenspeicher showed that only the full name, the Personal Identification Number, the address, and the agency were written in plain EBCDIC. All the other data fields were coded by numerical values, represented as binary figures.
Characteristics of the recovery
Without a precise description of the data file structure, there was no way to understand the meaning of the data. Therefore, it became clear that as much information on the Kaderdatenspeicher as possible was needed. The orders and commissions to create and process the Kaderdatenspeicher came from the Council of Ministers. The vertical files of this office had been added to the collections of the Federal Archives in Potsdam after unification. After searching these holdings for references to the Kaderdatenspeicher project, a series of records that contains descriptions of the Kaderdatenspeicher and reports from the data processing center with a lot of substantial information could be found. These paper records provided information on the content, purpose, history, and development of the Kaderdatenspeicher project, in particular:

• who planned the Kaderdatenspeicher and who gave the orders,
• which agencies cooperated,
• what the different aims and purposes of the Kaderdatenspeicher were,
• what information was contained in the Kaderdatenspeicher,
• how information was collected,
• which versions and updates of the Kaderdatenspeicher existed and which computer centersprocessed and stored them,
• who had access to which portions of the information contained in the Kaderdatenspeicher,
• and how information was used.

The reports to the Council of Ministers also contained information on the data file structure and codebooks. The Kaderdatenspeicher consists of annual compilations, so-called “generations” of data files for the year 1980 and for each year from 1985 to 1989, as well as of extracts for various purposes. Almost all of these data files have at least a slightly different structure. Nevertheless, the data file structures of all generations of the Kaderdatenspeicher could be found. Much information could be inferred from so-called “address tables”, which represent the record layout of a specific file.
The data files of the Kaderdatenspeicher were closely linked with the so-called staff databases of ministries and separate government branches, containing personal data of staff members. All the data of the Kaderdatenspeicher were originally collected from these staff databases. The Federal Archives has been successful in acquiring a relatively comprehensive and complete documentation of the staff database of the Ministry of Public Education. Therefore, additional information on the record layout and the data file structure of the Kaderdatenspeicher could be derived from the documentation of the staff database of this ministry.
In order to obtain background information, archivists have also made contacts with former employees of East German data processing centers who had created or worked with the data holdings which were acquired. In rare and difficult cases, for instance, when compression algorithms were used which could not be deciphered, programmers from former East German data processing centers were even hired as consultants.

Cost of the recovery
The cost of the recovery, made possible thanks to a joint effort of the Federal Archives, the University of Jena and the Center for Historical Social Research in Cologne, has been estimated by the Direction of the Bundesarchiv at something between 150,000 and 200,000 EUR, two thirds of it being invested by the Federal Archives.
Conclusions
The positive outcome of the recovery of the Kaderdatenspeicher was made possible due to two fundamental conditions: the discovery of paper-based documentation which, even though not directly descriptive of the archive, made it possible to identify the structure of the data files and therefore decipher their meaning, and the identification and collaboration of former employees of East German data processing centres who contributed, with their oral memory, to the deciphering of otherwise incomprehensible compression algorithms.

Source: Preservation of digital memories: risks and emergencies
Six case studies. Edited by Alessandra Ruggiero. http://www.iccu.sbn.it/upload/documenti/emergenze.pdf   (last accessed 02-02-2013)