I realize that there have been hundreds of questions about extracting digits or numbers from strings. This question is somewhat different.

I am looking at world bank data, and trying to get rid of the arbitrary regions they force into the data (e.g. High income countries). The approach I feel makes sense is to remove the observations for which
Code:
iso2code == "" | strmatch(iso2code,"X*") | strmatch(countryname,"*income*") | strmatch(iso2code,"%?") | strmatch(iso2code,"?%") | strmatch(iso2code,"%%")
There are no real countries for which ISO 2 code doesn't exist, starts with "X", or contains a digit, (nor a name that contains the word "income") while some of world bank's groupings do have iso2codes like so.

Of course, in the above I have totally made up
Code:
strmatch(iso2code,"%?") | strmatch(iso2code,"?%") | strmatch(iso2code,"%%")
to illustrate what I want to do...in this % represents a digit. So I want to tell Stata to drop the observation if iso2code string contains a digit.

A bit stuck on how to do that...