Hi Gord, thank you for your reply and sorry for not defining correctly.

The name strings in the two columns, first & last name, can't contain any
characters other than A-Z, a-z, 0-9. No accented characters or symbols. I'd
like to identify these entries with some type of marker so they can be
manually checked.

I'm not looking to auto replace them, just identify them - possibly with a
cell highlight but open to suggestions.

The system we load these names into doesn't support uni-code (yet) and we
get failures on large sheets due to this (we sometimes miss them on the
manual check).

From your instructions I've used =CHAR(ROW()), it's probably easier to list
the one's we'd like to allow as this is a smaller list.

Rows: 46 (full stop), 48-57 (0-9), 65-90 (A-Z) and 97-122 (a-z)

Not quite a sequential series, but could these be grouped maybe?

Thank you for your time, it really is appreciated.

Kind regards,

Gareth