(PECL svn >= 0.1.0)
svn_auth_get_parameter — Retrieves authentication parameter
$key
   )
   Retrieves authentication parameter at key.
   For a list of valid keys and their meanings, consult the
   authentication constants list.
  
keyString key name. Use the authentication constants defined by this extension to specify a key.
   Returns the string value of the parameter at key;
   returns NULL if parameter does not exist.
  
This function is EXPERIMENTAL. The behaviour of this function, its name, and surrounding documentation may change without notice in a future release of PHP. This function should be used at your own risk.