How does CFB determine which variables are on a template?

G’day
Quite often (although not all the time), if one is typing some code and one wants to reference a variable, one can start typing its name, press CTRL-SPACE and CFB will show a drop-down of variables matching what’s been typed in thusfar; one can then select a variable, and CFB completes it for you.  Excellent.

Except that it seems very flaky, often not picking up some variables (but is fine with others).  I wondered if variables were only "noticed" wn the file is saved or something, or every 5min or [I dunno, they were random guesses].  I could find no rhyme or reason to it.  I could type in two <cfset> statementes:

<cfset someVar = "foo">
<cfset someOtherVar = "bar">

And someVar would be offered, but someOtherVar would not be.

Sometimes variables wouldn’t show up for a while, but later I’d notice they would be.

Weird.

What’s the mechanism in play for populating the dropdown?

--
Adam