i am using koha 22.11 version 

i want to disable the indicator box and box for (a) (b) (c) etc so user can not type and change the [a] [b] [c] to [e] [f] [3] etc. On adding/modifying books koha page koha/cataloguing/addbiblio.pl when i click on 245 (a) it allow me to change (a) i want to disable/readonly [a] and two boxes for indicators so it cannot be changed.is there any system preference value to restrict the user? or any other suggestion?  

should i look into MARCOverlayRules ?

needed help in this problem.
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