@mhvk, can you clarify why you think it needs to be typeset as `hms` specifically for LST?  My point is that it nominally is actually a *time* rather than an angle, and it may be confusing to have it yield an angle. 

So it may be that this really means we want a way to string-format quantities with units of time as `hh:mm:ss` and such... but that would be for a separate PR to make it general.