How to specify CSS Classes

Hey All

I am checking in on the correct syntax use to specifiy a class for a CSS attribute as below:
Attachment 2551

Then we have this definition as an example:
Attachment 2552

Notice the later has a more explicit Path spec.
What is the difference?

Thanks Paul

app:/filename is correct.

Further discussed with Paul on existing ticket.

See Special Filename Prefixes for more on prefixes such as app:/ or lib:/