between programming languages; 
by non-programmers. 
Must provide reference to externally-defined syntaxes. 
Must be flexible, contractable, and expandable to allow the DDR 
to be built with a minimum of overhead. 
Must be able to be written with standard word processors. 
These will not be belabored here. Suffice it to say, that the TSDN has 
been designed to try to meet these requirements and attributes. 
Specifically, the TSDN permits the sender to describe the transferred 
information and to send this description separately or as an integral part 
of the transfer file. It permits the description of both character and 
bit field information in fixed- (without delimiters) or variable-width 
(delimited) fields or subfields. It further permits the identification 
of fields and subfields by arbitrarily long names and labels which serve 
to give meaning to the data. In addition, it provides for the 
definition and labeling of complex structures and commutated data. 
The Goal 
The intent is to supply the data product user with the conceptual or 
logical description of the data as well as the format and representation of 
the data. This information may be packaged with the data such that a suite 
of standard software at the user’s installation can transform the data to 
conform to his machine architecture and can present standard views for 
applications. 
Why is Something New Needed ? 
Type declarations in programming languages define the element formats as 
they occur within the closed system of the hardware/operating system 
housing the analysis program. Inasmuch as these declarations are different 
from language to language, and do not pretend to describe the formats as 
the data are transferred, a common notation for describing the data during 
interchange is required. 
The Problem 
Analysts may be expected to work in an environment in which there is a need 
to retrieve data from various files, either local or in archives, generated 
recently or decades ago, and to present that data to the analysis system in 
a usable, verified form. The files may be expected to be in various 
formats, using various numerical representations. The applications 
requiring the data may be expected to be in any one of a number of 
languages. For the system to be useful, a simple and consistent interface 
to the user programs is needed. Such an interface should be able to 
respond to a request from a user analysis program containing elements such 
as: 
retrieve 
from 
name 
format 
<a data element, by name, as found in the descriptive file> 
<archive and filename of the file containing the data element> 
<new name as required by the analysis program> 
<format in the user computer/language application> 
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