nsIRequest Interface

 Listed below are the various load flags which may be or'd together.


 No special load flags:

const unsigned long LOAD_NORMAL = 0

 
 Don't deliver status notifications to the nsIProgressEventSink, or keep 
 this load from completing the nsILoadGroup it may belong to.

const unsigned long LOAD_BACKGROUND = 1

 The following flags control the flow of data into the cache.


 This flag prevents caching of any kind.  It does not, however, prevent
 cached content from being used to satisfy this request.

const unsigned long INHIBIT_CACHING = 128

 This flag prevents caching on disk (or other persistent media), which
 may be needed to preserve privacy.  For HTTPS, this flag is set auto-
 matically.

const unsigned long INHIBIT_PERSISTENT_CACHING = 256

 The following flags control what happens when the cache contains data
 that could perhaps satisfy this request.  They are listed in descending
 order of precidence.


 Force an end-to-end download of content data from the origin server.
 This flag is used for a shift-reload.

const unsigned long LOAD_BYPASS_CACHE = 512

 Load from the cache, bypassing protocol specific validation logic.  This
 flag is used when browsing via history.  It is not recommended for normal
 browsing as it may likely violate reasonable assumptions made by the 
 server and confuse users.

const unsigned long LOAD_FROM_CACHE = 1024

 The following flags control the frequency of cached content validation
 when neither LOAD_BYPASS_CACHE or LOAD_FROM_CACHE are set.  By default,
 cached content is automatically validated if necessary before reuse.
 
 VALIDATE_ALWAYS forces validation of any cached content independent of
 its expiration time.
 
 VALIDATE_NEVER disables validation of expired content.

 VALIDATE_ONCE_PER_SESSION disables validation of expired content, 
 provided it has already been validated (at least once) since the start 
 of this session.

 NOTE TO IMPLEMENTORS:
   These flags are intended for normal browsing, and they should therefore
   not apply to content that must be validated before each use.  Consider,
   for example, a HTTP response with a "Cache-control: no-cache" header.
   According to RFC2616, this response must be validated before it can
   be taken from a cache.  Breaking this requirement could result in 
   incorrect and potentially undesirable side-effects.

const unsigned long VALIDATE_ALWAYS = 2048