TcM

Data Dictionaries, a brief explanation
Data dictionaries are how we organize all the data that we have into information. We will define what our data means, what type of data it is, how we can use it, and perhaps how it is related to other data. Basically this is a process in transforming the data ‘18’ or ‘TcM’ into age or username, because if we are presented with the data ‘18’, that can mean a lot of things… it can be an age, a prefix or a suffix of a telephone number, or basically anything! Maybe even an answer of a sum. But if we are presented with Age = 18, then that data is now information to us… because we know what that data represents, in this case that represents the age of someone. And to make an example of what how data can be related to other data, if for example we are presented with the data ‘TcM’, ‘18’ that can mean anything. But if we have Username = TcM, Age = 18 we know that the 18 is related to TcM, and it represents the Age of TcM.

Why use Data Dictionaries?
We use data dictionaries because we know what that data means, so we know which data to use and when, what data is needed for a certain operation, what type that data is, and when we are designing a system we can define the type, for example an integer, of that data. So it will lead us to a more stable system / program and better documentation for the end-user and other technical people. Besides that Data Dictionaries can define what that data means in real-life.

What is their use?
Well, one basic usage that came into my mind while writing this, this can help us design a class and to break down programming problems (read my previous blog for more information). This can help you define and design the classes needed to solve a certain problem. As an example (related to my previous blog) we can define that Account or User class will have for example a string representing the name, another string is representing the number, an integer being the PIN number. As you can see, we are defining the data type and what it represents.

Data Dictionary Format
Well, Data dictionaries vary in their format but usually their basic and most used format to have complete information about our data is:
Name
Alias
Where-used
How-used
Content Description
Supplementary Information

Data Dictionaries Notation
As many things in computing, these too have some notations, which are:
= means is composed of
+ means Sequence, and
[ | ] means Selection, either-or
{ }ⁿ means Repetition, ‘n’ repetitions of
( ) means Optional Data
* * means Delimits comments