As you know (hopefully!), custom tags in CF can be run in multiple execution modes. Specifically, you can build a custom tag so that you can call it like so:

<cf_bold>
Foo
</cf_bold>

Your custom tag can check to see which mode it is being called in by using a built-in scope, ThisTag:

<cfif thisTag.executionMode is "start">
   <b>
<cfelse>
   </b>
</cfif>

The executionMode key will be set to start when the tag is run the first time, and end when the tag is closed up with a matching pair. But what if you need to specifically call the tag in it's "end" mode? You can't set the value of thisTag.executionMode directly. However, you could tweak your code slighty like so:

<cfparam name="attributes.executionMode" default="#thisTag.executionMode#">

<cfif attributes.executionMode is "start">
   <b>
<cfelse>
   </b>
</cfif>

Now you override the execution mode of your custom tag on a case by base basis:

<cf_bold>
Foo
</cf_bold>

<cf_bold executionMode="start">
Another Foo
<cf_bold executionMode="end">