There are several standard HTML variables that are available in every .html
file:

  request - The full HTTP request line.
  cause - The abbreviated cause of the error condition.
  clientip - The IP address of the client making the request.
  clienthost - The hostname of the client making the request.
  version - The version of tinyproxy.
  package - Presently, resolves to 'tinyproxy'.
  date - The current date/time in HTTP format.

In addition, almost all pages support:

  detail - A detailed, plain English explanation of the error and possible
  causes.  You might consider this the Microsoftian error message.
