There are suggestions on the Idea Exchange to annotate subVI nodes with various attributes (this one, for example). I think that's a losing strategy. There just isn't space for all the annotations that might be of interest on a given node, and not all of the annotations make a difference to user's understanding of a given node. As an example, knowing that a subVI is reentrant is very important to understanding how a point-by-point read subVI works but unimportant to understanding how Trim Whitespace works. Also, not all of the annotations that we could imagine are simple "on or off" settings. A subVI that uses a local variable might be using it in an iterative algorithm or might be using it to store state between calls. If it is storing state, that might be something that a caller should know about.
These are the sorts of things that could be scanned for on a VI when LabVIEW launches the Icon Editor. If we had standard glyphs for interesting attributes of a VI, LabVIEW could have a section to recommend glyphs to add to the icon. This would not be an automated "always add this glyph" system that some people have requested because I do not think that we want the glyphs on every node just because it has the attribute. But some nodes it is worth calling out, and putting it in the Icon Editor would make it easy to add such glyphs. We might even have a fast "add recommended and arrange layers" button that spills all the glyphs onto the icon and then moves them around to minimize overlap, taking the existing layers into account.
