How to let custom meta data (boolean) change if certain tag exists (w Applescript)

Thanks for your suggestions . I had another trial/error session but succeeded:

property tagDelimiter : "xxx"

tell application id "DNtp"
	if (selected records) is {} then return
	repeat with theRecord in (selected records)
		set recordTags to tags of theRecord
		repeat with theTag in recordTags
			if theTag begins with tagDelimiter then
				set md to true
				add custom meta data (md as boolean) for "yyy" to theRecord
				exit repeat
			end if
		end repeat
	end repeat
end tell