Some times, you want to hide a field in frontend or backend item edit form or in both.

For example v1.5.6 has new parameter to FORCE a default value in a text field without ever needing to save any field value in the database.
The above can be useful if you want to add a field to all your (thousands) items without need to re-edit them.
This becomes really useful for triggering specific plugins inside the text field, that donot require per item value !!!

To define a field as being hidden in the edit form for e.g. field myfield:

Edit the file myfield.xml

To hide in backend, add parameter backend_hidden parameter, then (a) open the field and (b) set parameter to YES and (c) save

<param name="backend_hidden" default="1" type="radio" label="Hide in backend form" description="">
   <option value="0">FLEXI_NO>
   <option value="1">FLEXI_YES>
</param>

To hide in frontend, add parameter frontend_hidden parameter then (a) open the field and (b) set parameter to YES and (c) save

<param name="frontend_hidden" default="1" type="radio" label="Hide in backend form" description="">
   <option value="0">FLEXI_NO>
   <option value="1">FLEXI_YES>
</param>

To hide in both frontend and backend, set both parameters to YES

For J1.6/J1.7/J2.5 use  field instead of param