Questions about keyword hierarchy

Question

I'm in the process of designing and building a keyword hierarchy for LR3.5, and I'm at a loss to understand a couple of things.
In the process of deciding how to build this, I've looked at a number of hierarchies people have posted to the web. One thing I've noted is that people sometimes have the same word in multiple hierarchies, and sometimes the same word as both a regular entry and as a synonym.  For example:
Architecture
      Building
          Church
                  {Cathedral}
          Cathedral
          Skyscraper.....
Cities
      Building
      Cathedral....
So what happens if I use the keyword building?
I *think* what will happen is that LR gives me a choice of selecting Building>Architecture OR Building>Cities.  Is that correct?   Is there a way to get Building, Cities AND Architecture? What happens if I select Cities?  Do I get ONLY cities, and none of the lower level keywords?
And I'm at a total loss about synonyms. If, while applying keywords to an image, I select the synonym {Cathedral}, under Architecture, what keyword(s) get assigned to the image?  What if I select Church?  And what if I select Cathedral under Cities?
Many thanks.

Answer 1

Thanks web-weaver.
I posted basically the same question in a couple of other places, and got conflicting answers. And the information I found on web searches tended to explain HOW to set up a hierarchy, but not how it really worked, and information on synonyms is especially limited, and often conflicting. So I did some tests.  So as to not use any words that were already in my keyword list, I built a simple hierarchy of words not currently in use:
Colors       
    Blue   
        {Cyan}
        {Azure}
    Red   
        Pink
                        Salmon
        Rose
    Green   
        {BRG}
        {Emerald}
    Cyan  
    Orange
Fruit
    Orange
    Apple
(I actually had a couple of other trees, but this is enough to demonstrate how they actually work.)   
And it turns out synonyms don't work quite like I expected them to, and are, honestly, so limited I question their value.
Test1:  Tag a photo with the keyword Cyan. Only Cyan gets applied to the metadata, not any of the words associated with it (Blue, Colors, Azure). Searching, I can find the image by searching on Cyan, or Colors. But NOT by searching on Blue.
Test2: Tag a photo with the keyword Blue. Only Blue gets applied to the metadata, not Cyan, or Azure. When searching, I can find it by searching on Blue, or any of it's synonyms (Cyan, Azure), or Colors.
(I had expected synonyms to work the other way, I think. So that if I searched on Blue I'd get all images tagged with Blue, but also those tagged with Azure and Cyan. )
Test3:  Tag one photo with Cyan, and another with Blue. Searching with Cyan gets me both images, as does searching with Colors. Searching on Blue gets me only the image tagged with Blue.
Test 4: Tag a photo with the word Colors (and nothing else). I find it by searching ONLY on colors, not Blue, Cyan, or Azure.
Test 5:  Tag a photo with the word Red (and nothing else). I find it by searching on Red, or Colors, but not Pink or Rose.
Test 6:  Tag a photo with the word Pink (and nothing else). I find it by searching on Pink, Red or Colors, but not Salmon.
Test 7: Tag one photo with Orange->Color, and a second image with Orange->Fruit (this nomenclature seems backwards to me, btw.  It's really Fruit-Orange and Color-Orange, but whatever...) Searching on Orange finds both images. Searching on Color finds only one, searching on Fruit finds only the other.
Synonyms affect only search, and not tagging (assignment). Searching on a term that is a synonym will find images tagged with the main word. (e.g., search on Azure and you'll find Blue, but not Colors). 
On another site someone replied that when you search you'll find "any image which bears that keyword or any keyword BELOW it in the hierarchy." That's backwards, at least as I understand the word "above.". You'll actually find images using the keyword, it's alias, or any word ABOVE it in the hierarchy. So if an image is tagged with Red, you can find it by searching on Red or Colors, but not Pink. If the image is tagged with pink, you can find it with Colors, Red or Pink, but not Salmon.
The worst limitation of using synonyms is that when you're tagging an image, LR3 isn't smart enough to know the synonyms exist. So if I tag an image with the word Azure, LR3 doesn't substitute Blue, or use the synonym where it already exists in the hierarchy.  Instead, creates a new, top level entry named Azure, not tied in any way to the alias or the "Colors" tree. 
It seems like it would be useful to be able to enter Blue as a search term and find any images tagged with Azure and Cyan. Or enter Red as a search term and find Pink and Rose, too. The way it's implemented now forces you to enter the term you're most likely to use (Blue, for example) at the bottom of the hierarchy, and the least used words above. Or to use synonyms, and hope you never get confused an enter a synonym as a keyword instead of the word it refers to.
It seems to me it's more useful to just use Azure as another keyword beneath (or maybe above) Blue in the hierarchy. At least that way if I tag an image with Azure, I'm not creating a new entry in the Keyword list. I'm not sure I see much value in synonyms as they're currently implemented, but if someone has some examples of how synonyms benefit them I'd be delighted to see them.
Hopefully this information will be of use to someone.