Hi,
In Action, I would like to add a default blank value for efficiency like this.

So if the user let it blank and submit, an error would occured saying, efficiency is mandatory.
How can I do it
Hello,
You can use plugin screen customization and set propertie of efficiency field to required.
So user can't submit without efficiency.
Thanks for the answer but do you know why does the non-required field have a blank value available and why the requested one doesn't?
It is the global design in ProjeQtOr : required fields avec no empty value available so that the first item becomes the defaut value...
It eases most entries.