That's a different request, and might be better handled by Data Validation
than Conditional Formatting.
If you can't define what may be put in the cell, just leave Any Value
selected in Data Validation, and use an Input Message as your warning when
they select the cell.

HTH
Steve D.



"JohnG" wrote in message
...
Thanks again Max. There are valid reasons for contributors to overwrite
these formulae where they have better information than the default result
from the lookup formula. My wish is to just have one extra prompt that
reminds them they need to be very sure of what they are doing when they
overwrite the formula
--
JohnG


"Max" wrote:

well, I'd suggest that you just protect all the formula cells then, do
not
allow any overwriting. You could always ask users who "dispute" the
formula
returns to indicate their own values in an adjacent col in their
submissions
to you, for example.
--
Max
Singapore
---
"JohnG" wrote:
Thanks Max - I am looking for an automatic solution as I also want the
less
experienced contributors to the spreadsheet to realise that they have
overwritten the default formula. I also prefer not to use VBA or
macros in
the solution as someone less experienced will need to maintain the
spreadsheet when I move on