title: Restrictions on characters in POST variable names
body: <p>I was recently surprised to learn that PHP will automagically and unpreventably turn all periods to underscores in the names of POST fields, because periods are not allowed in variable names in PHP.</p>
  
  <p>I have POST data that is keyed with names that have arbitrary data in them, and I was thinking about Base64 encoding the POST names to avoid the period problem. However, the Base64 alphabet includes the characters <code>+</code>, <code>/</code> and <code>=</code>. These letters are also not allowed in variable names, but are these alright for POST names? What will PHP do with them?</p>