If your question is how to view the actual ordinance through Loudoun County's website then:
1) Go to "Loudoun County Ordinances"
2) Click "Part Six: General Offenses (Chapter 602-692)"
3) Click to open "Chapter 654-Offences Against Public Peace and Safety" (PDF)
4) Scroll down to 654.01(d)
It is "unlawful...to fail to identify [one's self] at the request of [an]...officer" when "at a public place or place open to the public." The requirement is "when circumstances indicate that public safety requires such identification."
For previous discussion of Stop & Carry look -> here. The highlights are quoted in that post and the original link to the main thread (5pgs) is there as well.