title: In JSP, what do the path and value attribute do within the input tag, and how does the form prefix affect them?
body: <p>Just wanted a clear answer for a direct question -- google results have been all over the place or don't address the combos you'll see below.</p>
  
  <p>I'm generally a JSP newbie and have been screwing around with the following code.</p>
  
  <pre><code>&lt;form:input id="theId" path="path.copied.directly.fromSomewhereElse"
      cssClass="contentTextInput" cssStyle="width: 229px" /&gt;
  </code></pre>
  
  <p>When I put that into my JSP page and load my website, it works fine and looks as my cssClass defines it.  Then I start messing with it because I want it to display a default <strong>value</strong>.</p>
  
  <pre><code>&lt;form:input id="theId" path="path.copied.directly.fromSomewhereElse"
      value="blah" cssClass="contentTextInput" cssStyle="width: 229px" /&gt;
  </code></pre>
  
  <p>Suddenly, HTTP 500, an org.apache.jasper.JasperException!  So I decide to <strong>remove the path</strong> altogether, while leaving in the value.  This is just step 1 in something I know works because of prior experience.  The code is now:</p>
  
  <pre><code>&lt;form:input id="theId" value="someClass.valueIWantAsDefault" 
      cssClass="contentTextInput" cssStyle="width: 229px" /&gt;
  </code></pre>
  
  <p>That actually throws an exception, too -- but then I remove the form prefix and it works-- mostly.  You see, the cssClass's effects are now gone; it looks like a regular, unaffected input textbox.  Here's the code so far.</p>
  
  <pre><code>&lt;input id="theId" value="someClass.valueIWantAsDefault" 
      cssClass="contentTextInput" cssStyle="width: 229px" /&gt;
  </code></pre>
  
  <p>What exactly do these attributes (and prefix) do that makes this mix-and-match work? </p>