How to Lock date
How to Lock date so it can't be selected by coincidently or changed
paid to the person on that date and LOCK it to that field once selected the date
its setted up drop down calender field
A script trigger, onObjectEnter can be used to perform a script to check to see if the field is empty. If not, it can use go to field, go to object or go to next field to move the cursor back out of the field if it is clicked. This will not prevent modifying the field via drag and drop, however so this method mainly prevents accidents not deliberate attempts to modify the field.
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