st: Using regex to identify strings with capital letters

["Beecroft, Erik (VDSS)" <erik.beecroft@dss.virginia.gov>]

I need to extract certain observations from a series of text files.
Each file contains only one variable, which is string.  The
observations I want all begin with two capital letters. (They are state
abbreviations, such as VA or AK).  The other observations do not begin
with two capital letters.

Is there a way to tell Stata to keep only observations for which the
variable begins with two capital letters?

It seems like the regex function might work, but I have never worked
with regular expression syntax before.  

For example, a portion of a text file might look like:
	text1
	text2
	VA department of Social Services
	text4
	text5

I want to keep only the third observation above.

I am using Stata for Windows 10.1.

Erik


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