 <p>These postfixes commonly says what is the role of the object.</p> <p>For objects intended to transfer data, it is common to add the <strong>TO</strong> suffix, so we have <code>ServerTO</code>, <code>AccountTO</code>, <code>UserTO</code>, <code>CompanyTO</code>, <code>CustomerTO</code>, <code>SaleItemTO</code>, etc. <strong>TO</strong> is an acronym for <em>Transfer Object</em>. A variation of this is the <strong>DTO</strong> suffix which means <em>Data Transfer Object</em>.</p> <p>For objects intended to control the database access we have the <strong>DAO</strong> suffix for <em>Data Access Object</em>, so we have a <code>UserDAO</code>, <code>CustomerDAO</code>, <code>SalesDAO</code>, etc.</p> <p>The <strong>UI</strong> or <strong>GUI</strong> suffix is frequently used for user interface objects. These are acronyms for <em>Graphical User Interface</em> or simply <em>User Interface</em>.</p> <p>Other common uses of this are <strong>VO</strong> for <em>Value Object</em> and <strong>DO</strong> for <em>Domain Object</em>.</p> <p>I once saw <strong>BE</strong> suffix for <em>Business Entity</em>, <strong>SL</strong> for <em>Service Locator</em> and <strong>PB</strong> for <em>Page Bean</em>.</p> <p>Although this is a common practice in lot of places, I weakly recommend against it. A descriptive name is normally much better than a cryptic acronym suffix (or prefix), but if you can't find one that is not too long, use the acronym. Instead of <code>CustomerTO</code> or <code>CustomerDTO</code> you could name it just <code>Customer</code>. Instead of <code>SalesDAO</code> you could name it <code>SalesPersistence</code> or <code>SalesDatabase</code>. This eliminates the problem of trying to understand what the suffix should mean when you get a <code>VendorDSA</code> or a <code>PersonTF</code>.</p> <p>In partcular the <strong>DTO</strong>, <strong>TO</strong>, <strong>DAO</strong>, <strong>UI</strong>, <strong>GUI</strong>, <strong>VO</strong> and <strong>DO</strong> suffix are very common and widespread. Other suffixes are normally obscure.</p> <p>For your case in special, I have no idea of what is <strong>SO</strong> and <strong>RO</strong>, and I can't do anything better than just guess, which again shows that a descriptive name is better than an acronym as a suffix. My best bet is that <strong>SO</strong> is <em>Service Object</em> and <strong>RO</strong> is <em>Resource Object</em>.</p>