<desc>A proplist containing the callback functions for the new Effect. The name (<funclink>GetName</funclink>) of this proplist becomes the name of the effect.</desc>
</param>
<param>
<type>int</type>
<name>priority</name>
<desc>Effect priority. Must be greater than zero.</desc>
</param>
<param>
<type>int</type>
<name>timer</name>
<optional/>
<desc>Interval for the timer calls. With <code>nil</code>, no timer calls are made and the effect stays on permanently until it is deleted by other calls.</desc>
</param>
<param>
<type>any</type>
<name>var1</name>
<optional/>
<desc>First extra parameter to be passed to <code>Construction</code>, <code>Start</code> and <code>Effect</code> callbacks.</desc>
</param>
<param>
<type>any</type>
<name>var2</name>
<optional/>
<desc>Second extra parameter to be passed to <code>Construction</code>, <code>Start</code> and <code>Effect</code> callbacks.</desc>
</param>
<param>
<type>any</type>
<name>var3</name>
<optional/>
<desc>Third extra parameter to be passed to <code>Construction</code>, <code>Start</code> and <code>Effect</code> callbacks.</desc>
</param>
<param>
<type>any</type>
<name>var4</name>
<optional/>
<desc>Fourth extra parameter to be passed to <code>Construction</code>, <code>Start</code> and <code>Effect</code> callbacks.</desc>
</param>
</params>
</syntax>
<desc>Creates an effect. Returns the effect if successful or <code>nil</code> if not (e.g. because the effect was rejected). If the effect was accepted by another effect which is deleting itself within the same call, the return value is probably <code>nil</code>. Effects can be created on objects, <code>Global</code> and <code>Scenario</code>. This is passed as the first parameter to the effect callbacks.
</desc>
<remark>For examples and more information see the <emlinkhref="script/Effects.html">effects documentation</emlink>.</remark>