Given a general ledger account entered into a cell on the spreadsheet that
looks like: 123.123.1234.123456.123.12.123

Using VBA, I need to be sure it only contains either numbers or periods and
no other stray characters (`,#$!-_=+ A-z ... etc), including blank spaces.
What is the best way to test for this?

Please note that I am already counting the periods to ensure the number of
segments and checking the length of each segment...

Thanks much in advance.