want to know about string type of attributes limitations and default string length and constraints.

Version: Windchill 12.1

Use Case: Created Reusable and global attribute and i used those in Manage types like WT Part, those attribute when i add and edit, i see the default constraint added and it was showing lock on first column. and it says modeled attribute. simply, i want to know about that modeled constraint and how it works and how it added. what is the limitation and advantage.

Description:

Hello Community,
I wanted to know about the Attributes which is type of string. that i want to know about default constraints windchill provide OOTB.
String length is maximum upto 2000.

what are modeled constraints how it gets added in attribute in type and attribute.
relevant documents or help or knowledgebase URLs would be help.