URI - Fragment (Ref, Reference)

The fragment is the last part of a URI.

It's also known as a:

• ref
• reference

An URI has the following syntax with the #fragment being the fragment

[scheme:][//authority][path][?query][#fragment] 

The value of the fragment must be encoded.

When a html navigation occurs (ie the uri is clicked or fired), the fragment represent:

• an HTML - Element's unique identifier (Id Attribute)
• or a HTML - dfn element (Defining term)
• or with an anchor name

<a name="smtpd_client_restrictions">smtpd_client_restrictions</a>

• https://tools.ietf.org/html/rfc3986#section-3.5