CFCs setting variables

Question

I am getting a bit confused with cfcs using cfreturn and
cfinvoke please be patient!
1.Setting variables in cfc
In this example cfc I make a query. The cfreturn tag does
<cfreturn expression /> as I understand it. I don´t
understand how you define the expression - can you return
arguments, any column I like in variables? How do I do that?
<cfcomponent><cffunction><cfargument
name="user">
<cfquery name="checkuser">
select col1, col2, col3, col4, col5, col6
from user
where .....=....
</cfquery>
<cfreturn checkuser.col1>
2. Calling cfc:
In cfinvoke you call a variable using returnvariable="". Is
it true that the variable doesn´t have to have the same name
as in the method that the cfinvoke tag is calling? What does return
variable call? How do I define what it calls?

Answer 1

In any cffunction, inside or outside a cfc, if you are going
to return a value, you use the cfreturn tag. You can return
constants like true, 1, "Dan is so smart", or variables. What you
return has to be consistent with the returntype attribute of your
cffunction tag.
When you invoke a variable, you can use any name you want as
the return variable. In theory, you don't even know any variable
names inside the function. The return variable does not call
anything. It accepts what the function returns.
It is the cfinvoke tag that calls something. You control what
it calls with it's attributes.
Further details are in the cfml reference manual.