User should not be able to edit characteristics Value

Hi Friends

I have requirement where in a user creates a document with Two characteristics assigned to that Document.

Say CHAR1 and CHAR2.

When he creates DIR , He assigns value to these characteristics

CHAR1 = 666454

CHAR2 = 55333

No I want No other user to be able to change the values assigned to both CHAR1 and CHAR2.

Can this be possible.

With Regards

Mangesh Pande