Guaranteed to be an unsigned 64-bit integer on all platforms.
#include <prtypes.h> typedef definition PRUint64;
May be defined in several different ways, depending on the platform. For syntax details for each platform, see prtypes.h.
Note: Prior to Gecko 12.0,
PRUint64 was actually treated as a signed 64-bit integer by XPConnect. This has been fixed.