How can we restrict the access/modification of Key Flex Filed Segments/Values of a particular module

Hi,

How can we restrict the access/modification of Key Flex Filed Segments/Values of a particular module in another module(s)?   The objective is to ensure the security of the important key flex field segments and values.

e.g.  GL Chart of Accounts Segments and values can be accessed and modified by using Invenory Responsibility also. Like Inventory Key Flex Fields Segments and values can be accessed in GL Responsibility.

Regards,

Krishnadas