what is meaning of following code

Hi   All,

I am working on transitiom plug-in for  premiere pro cs3 ,using  premiere pro cs3 SDK.

while learning i am not get understand the following code, where will be use and what will be function of this code

also, did not understand the code which is mark below in the red.

static prMALError Execute(EffectHandle theData)
{
    prMALError        result                = esNoErr;
    prRect            bounds                = {0,0,0,0};
    PPixHand        destPPH                = ((*theData)->destination);
    SPBasicSuite    *SPBasic            = NULL;
    PrSDKPPixSuite    *PPixSuite            = NULL;
    float            transitionProgress    = 0.0f;
    PrPixelFormat    pixelFormat            = PrPixelFormat_Invalid;

    prBool            **specsH            = reinterpret_cast<prBool **>((*theData)->specsHandle);
    if (specsH == NULL)
    {
        // If specsH has not been initialized and is NULL, render with the default settings
    }
    else
    {
        // Render using user-controlled setting
    }

    ((*theData)->piSuites->ppixFuncs->ppixGetBounds)((*theData)->destination, &bounds);

    // Sample code - not really necessary for the functionality of this plug-in
    DemoUsingInstanceData(theData, &(*theData)->instanceData);
    DemoUsingCallback(theData, bounds);

    // Get pixel format of PPix
    SPBasic = (*theData)->piSuites->utilFuncs->getSPBasicSuite ();
    if (SPBasic)
    {
        SPBasic->AcquireSuite (kPrSDKPPixSuite, kPrSDKPPixSuiteVersion, (const void**)&PPixSuite);

        if (PPixSuite)
        {
            PPixSuite->GetPixelFormat (destPPH, &pixelFormat);

            SPBasic->ReleaseSuite (kPrSDKPPixSuite, kPrSDKPPixSuiteVersion);
        }
    }

    transitionProgress = (float)(*theData)->part / (float)(*theData)->total;

    // Render the transition
    RenderDissolve(theData, &bounds, pixelFormat, transitionProgress);

    return result;
}

Thanks,

waiting fir reply