#DSN#

In many CF examples, I see the dataSource is specified with a variable, such as
<cfquery datasource="#DSN#" name="TEST">
The rational has been to assign the variable once and reuse it in every reference to the datasource rather than hard code it.
To me, hard coding it didn't seem to be that big of a burden - just use a global search and replace if you change your mind.  Besides, the dataSource name is only a pointer to the data source defined in cfide/administrator.
It was when I started cutting and pasting examples that I saw the wisdom of using a variable instead of hard coding my dataSource name.  I don't want search engines spidering my keyword dataSource name if I use it in a Newsgroup or Experts-Exchange.  By using a variable, I can keep my examples generic.

Now, the question is: What is the BEST way to specify the dataSource name?
Define it once on application startup in the Application scope?
Define it upon every onRequestStart using the Request scope?
Define it as a Session variable?  
Define it as a a Client variable?
Define it as a Form variable?
Define it as a Variables variable?
Define it with the THIS keyword?
Define it as an URL variable?  (OK, now I'm getting a little bit ridiculous).

An unacceptable answer is "it depends".
For the purpose of this discussion, the dataSource name will be static throughout all the pages on the site.
If you are stuck on the "it depends" answer, then choose a scenario and address it, but don't answer with "Depends".

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