Blocking specific cells

[Natale]

Hi all!
I need to set that if a cell contains "ND" or "AG" value, a third user can't write "L" value in upper and lower cells.
Please, see attached file: all "L" you see must be not writable in that cells.

Also, is it possibile to set the same function in Google Sheet (online)?
Thanks!

[Kaper]

In C2 set data validation as custom and use formula:

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copy this cell, select all interesting cells (C2:AH32) and in paste special dialog select data validation and OK

See in attached file (of course what has been written before remains there, but if you try to edit the cell with L and AG or ND below or above the data validation will not allow you to change it).

As for other spreadsheet software - have no foggiest idea

[Natale]

Hi, Kaper!
Thank you very much!

Formula partially works. You can try also in file you attached: if in C2 you write "L", data validation blocks it. Instead, if yuo write "L" in C4, nothing happens.
Also, if I write "L" in C2, then "ND" in C3, data validation doesn't block it!

I forgot in previous message: if cell contains "ND", user can't write "AG" (and vice versa).

Best regards,
Natale