I don't think you can post a variable by means of a link. For
example, doing <a href="myPage.cfm?form%2Etopic=123"> wont
work. A link cannot create the form scope on the action page. Only
tags like <form> and <cfhttp> can.
However, if you insist on using a link, Javascript could come
in handy.
sender.cfm:
<a href="javascript: document.poster.submit()">Post
it</a>
<cfform name="poster" action="myPage.cfm" format="HTML"
method="POST">
<cfinput name="topic" type="Text" value="123">
</cfform>
myPage.cfm
<cfif isDefined("form.topic")>
form.topic: <cfoutput>#form.topic#</cfoutput>
</cfif>