Best Practice for References - Memo, Text and Text Long

[shiju01]

Hi community

When and where to use Reference  

(http://www.adempiere.com/Application_Dictionary)


 a) Memo                      - Large Text Editor - Character String up to 2000 characters

 b) Text                        -  Character String up to 2000 characters

 c) Text Long                - Text (Long) - Text > 2000 characters

 d) String                     - Character String

What should be the corresponding postgres data types for each of them when defining the table by ddl?