I'm editing a code written by someone who left nearly no comments. I'm trying to find where does a parameter in a `httppost` function come from. (`ism` in this case).

```
 [HttpPost]
 [SessionCheckFilter]
 [LogFilter]
 [ValidateInput(false)]
 [ActionName("Save")]
 public ActionResult Save(StructureViewModelPOST ism){...}

```

The thing is, `StructureViewModelPOST` is only used in this function. There are no other references to it. I want to change the data in the `ism`, but I have no idea where it comes from. This function is called when someone presses the "save" or "save and close" button inside my form

```
<a class="btn btn-primary fixed-width navigation"  href="#" onclick="checkTotalValue(1);"><i class="icon-save pull-left navigation"></i>Save</a>

```

And the form is created like this inside my view: 

```
@using (Html.BeginForm("Save", "Invoice", FormMethod.Post, new { @class = "form-horizontal" }))

```

I realise i'm not providing you with all the information necessary to answer this quesion, but I can't just paste the whole project and I don't really know what information IS needed to answer it.