Every project has a special need to collect some extra information. 2.0 introduces “Dynamic Field management”. Now, Story /Task / Issue all can have dynamic fields and can be setup from Project Settings.
Go to Project Home> Settings.
In Story, Task, or Issue Dynamic field you can set Date, Radio Buttons, Checkboxes, Text, Dropdown etc..
Set permission to display Dynamic fields in story, task and Issue page. Permission can be defined Role wise.
After creating the Dynamic fields only permitted user can use that in story view, task view and issue view by clicking on 
link.