Can I prefix with $ (dollar sign) my URL query string parameters safely?
<p>I am starting to implement filtering through query strings in my API REST application where I can perform filtering on any field passed to a entity in my database. But there are especial parameters that I want to differentiate like; <code>sort</code>, <code>page</code>, <code>direction</code>, etc from the rest of fields that will be used to filter the collection.</p>

<p>I want to avoid using an implementation like:</p>

<p><code>/?filters=field1:value1,field2:value2&amp;page=3&amp;per_page=50</code></p>

<p>Because I will need to make a custom parser to the <code>filters</code> value.</p>

<p>My desired structure is something more plain, like this:</p>

<p><code>/?lastname=Halden&amp;country=somewhere&amp;$sort=lastname</code></p>

<p>So, all the properties that aren't prefixed with <strong><code>$</code></strong> are used to make the filter and the other properties with the prefix are used to tweak the result.</p>

<p>My actual question is that if <strong>it is safe</strong>?. If there can exist a problem in the moment to parse the whole query string in some libraries.</p>