<p>In the meantime, this was extensively discussed in the answers and comments in <a href="https://stats.meta.stackexchange.com/questions/4669">Tags around categorical data coding / representation</a> and the outcome was as follows:</p>
<ol>
<li><p>Master tag <a href="https://stats.stackexchange.com/questions/tagged/categorical-encoding" class="post-tag" title="show questions tagged &#39;categorical-encoding&#39;" rel="tag">categorical-encoding</a> has been created, and has the following three synonyms: <code>[dummy-variables]</code>, <code>[indicator-variables]</code>, and <code>[one-hot]</code>. It currently has 67 threads.  Wiki excerpt:</p>
<blockquote>
<p>Representing categorical variables as sets of numerical variables. Necessary in many types of analysis for them to process categorical data. A common example is using a categorical predictor in regression/ANOVA via dummy coding, effect coding, Helmert coding, user-defined contrasts, etc.</p>
</blockquote>
</li>
<li><p>New tag <a href="https://stats.stackexchange.com/questions/tagged/indicator-function" class="post-tag" title="show questions tagged &#39;indicator-function&#39;" rel="tag">indicator-function</a> was created for mathematical or notational questions about indicator function, that have nothing to do with encoding categorical variables. It currently has 16 threads. Wiki excerpt:</p>
<blockquote>
<p>A function defined on a set indicating membership in a subset and taking values 0 and 1.</p>
</blockquote>
</li>
</ol>
