bute is
 an "="-separated name-value pair with the name in lowercase. Each
 name-value pair is semi-colon (";") separated.  The following names
 are defined.

 <table border=1>
 <caption>
 Attribute Names in Providers Files
 </caption>
 <tr>
 <th>Name</th><th>Description</th>
 </tr>
 <tr>
 <td>protocol</td>
 <td>Name assigned to protocol.
 For example, <code>smtp</code> for Transport.</td>
 </tr>
 <tr>
 <td>type</td>
 <td>Valid entries are <code>store</code> and <code>transport</code>.</td>
 </tr>
 <tr>
 <t