Default value of column in information_schema

[Юра Величко <velichko.yuriy@xxxxxxxxx>]

Hello everyone!

I have a next question:

Is there some rule, that sets default value in the information_schema.COLUMNS.column_default ?

Because for integer is - 777, and for character varying is -  'Hello world'::character varying

I don't find description of this rule. 

I need to know it, to clean up unused symbols from types like character varying, and show it.

Thanks.