Distinguishing tags from (ordinary) groups in scripts

tell application id "DNtp"
	set sel to (selected record 1)
	(*
	Tag: {group, ordinary tag}
	Group Tag: {group, group tag}
	Group: {group, no tag}
	Document: {x, no tag}
	*)
	
	return tag type of sel is in {group tag, ordinary tag}
	-- If true, then it's a tag of some type
	-- If false, it's a group or document
end tell

What are you trying to do?

PS: @cgrunenberg. Not sure if you know the reason for the difference shown below…

tell application id "DNtp"
	set sel to (selected record 1)
     --This resolves as false when a group is selected. Not sure why.
	log{type, tag type} of sel = {group, no tag}
	
     --This works when a group is selected…
	set {type:t, tag type:tt} to sel
	return {t, tt} is {group, no tag}
end tell