Issue Description:

The name of this label should be something starting with "truncating," since its only reason for existence is to warn the reader that it might truncate, and because the corresponding old labels begin that way. I keep finding myself typing "truncatingOrExtending" instead of what it actually is. The fact that extension is a possibility is almost not relevant in any case I can think of, since you can always use the label-less constructor in those cases, and only serves to clarify behavior in the most generic contexts.