---
title: "EFF file format"
regenerate: true
---
    {% include relurl.html %}
    <div class="title_main">EFF file format</div>
    <br />
    <div class="fileHeader">Applies to:</div>
    <div class="indent1">BG1: TotS, BG2, BG2: ToB, IWD, IWD:HoW, IWD:TotL, PST, BGEE</div><br />
    
    <div class="fileHeader">General Description</div>
    <div class="indent1">
      This file format describes an effect (opcode) and its parameters. The format is only ever found embedded in other files (e.g. <a href="../ie_formats/itm_v1.htm#itmv1_Feature_Block">ITM</a> or <a href="../ie_formats/spl_v1.htm#splv1_Feature_Block">SPL</a>). The engine appears to roll a probability for each valid target type, rather than one probability per attack.<br />
    </div>
    <br />
    
    <div class="fileHeader"><a name="effv1">EFF V1.0</a></div>
    <div class="indent1">
      Overall structure:<br />
      <div class="indent1">
        <li><a href="#effv1_Header">Header</a>
      </div>
      <br />
    </div>

    {% assign offset_header_name = "effv1_Header" %}
    {% assign offset_header_display_name = "EFF V1.0 Header" %}
    {% assign offsets = site.data.file_formats.eff_v1.header %}
    {% include offset_table.html %}

  </div>
</div>