Should technical debt be scheduled as a feature or a chore (or a bug)?

Question

I've added a couple of user stories that address some technical debt to my Pivotal Tracker board. Should I consider them as features (keeping my velocity level) or as chores/bugs (lowering my velocity)? I understand it won't make any difference in the long run if I did one or the other consistently, but every time I add a technical debt story I have to make the decision.

Some thoughts:

• They aren't actually bugs, they don't break anything
• The users haven't requested anything as it is low-level implementation that doesn't affect them, but it will make long term development easier
• If you define features as stories that add value to the users, well a) they don't as the users won't see any direct benefit, but then b) they do because they make future development/maintenance possible which does add value, just not right now

I'm not deciding whether or not to actually do the work, or when to schedule it, I just what to know what I should call technical debt in my project management tool, and why.