How do we think morale (+) bonuses are supposed to work?

[Nevill]

I'll preface this post with Maniac's excellent Treatise on Morale: http://apolyton.net/showthread.php/145615-Treatise-on-Morale?postid=4195589

So, we know how does it work, and it is pretty much borked. However, the trickier question is, how is it supposed to work?

The question I'd like answered are:
1) What exactly is a (+) sign and what should it affect? (which is what this thread and poll are for)
2) What exactly is a (-) sign and what should it affect?
3) What should affect the number of (+)/(-) signs the units have?
4) What other bugs are there due to a botched implementation of morale, and what could be done about them?

Let's start with 1). Here is an excerpt from the Treatise:

For some units you will see there are one or more (+)'s behind their morale level. What is the meaning of those? Unfortunately there is no consistent rule for their effect. For instance, the (+) after Very Green morale level means a permanent +12.5% defence bonus in battle, both in and outside bases. On the other side the (+)'s received as a consequence of a positive SE Morale have a more limited effect. They only provide a +12.5% bonus when a unit is defending from attack inside a base. In the open the (+)'s have no effect whatsoever. Also 'Elite (+)' gives no extra bonus beyond 'Elite''s +50%.
And when we start talking about (+)'s received as a consequence of Children's Creches, there is little logic at all anymore to be detected behind the (+)'s.

And here is one that made it to Googly's Datalinks:

A unit with a "+" sign after its morale possesses a combat bonus from its location in a base with a $LINK<Children's Creche=100002>.

So, is there a consensus what a (+) should represent? Should they even have a common meaning?

I believe that, yes, they should,

You get a (+) under one of the following conditions:
1) As a part of choosing a positive MORALE settings to indicate a better ability to defend in a base.
2) As a part of being in a base with Children's Creche, which has a flavor text about parents defend their home to the death.
3) Automatically for Very Green units (which I believe is a bug - all Very Green units have a (+) that can"t be 'removed' from them - we'll talk about it later).

Does anyone else know the circumstances under which a unit gets (+) marks?

So from these I assume that (+) should confer purely a defensive bonus. Do you agree?