RMS Security issue

Hi Experts.

Please look in below details and help me to understand it

 

1- Select * from NAV_ELEMENT_MODE
2- Select * from NAV_ELEMENT_MODE_ROLE

In above Query there is a column NAV_MODE, this column contain value

NAV_MODE
=======
ITEM
NEW
-DEFAULT-
EDIT
VIEW

Where and how can I use these value and what will be their affect on application.

i.e.

form ordfnd is with nav_mode= "-DEFAULT-" so if I change it to ITEM or NEW or EDIT or VIEW what will happen

Thanks