Wrapper is readable (almost always true). File core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface

Visible, readable and writeable. File core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php,

public StreamWrapperInterface::dirname($uri =

This is the default 'type' falg. This does not include StreamWrapperInterface::LOCAL, because PHP grants a greater trust level to local files (for example, they can be used

public StreamWrapperInterface::realpath()

A filter that matches all wrappers. File core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface.php

Refers to a local file system location. File core/lib/Drupal/Core/StreamWrapper/StreamWrapperInterface

public StreamWrapperInterface::setUri($uri)

Defines a Drupal stream wrapper extension. Provides a Drupal interface and classes to implement PHP stream wrappers for public, private, and

public StreamWrapperInterface::getDescription()