Techwiki:Win32k/BASEOBJECT
The GDI Base Object, which is a header at the top of every GDI Object. The structure is called _BASEOBJECT and is defined as follows for Windows XP and Windows 2003 :
struct _BASEOBJECT { HANDLE hHmgr; // Handle for this object ULONG ulShareCount; LONG cExclusiveLock; // lock with InterlockedIncrement or not PW32THREAD Tid; // contain which thread it belong to, PsGetCurrentThread() ULONG BaseFlags; } BASEOBJECT, *PBASEOBJECT, DD_BASEOBJECT, *PDD_BASEOBJECT, *POBJ;
The pointer to a _BASEOBJECT is known as a POBJ.