pdfUnlockDocument

BOOL32 __stdcall pdfLockDocument(PPDF IPDF);
BOOL32 __stdcall pdfUnlockDocument(PPDF IPDF);

function pdfLockDocument(const IPDF: PPDF): LongBool; stdcall;
function pdfUnlockDocument(const IPDF: PPDF): LongBool; stdcall;

Purpose. Acquire/release a document-level lock — for coordinating access across the caller's own multiple threads (this SDK's own general threading rule is still "one PPDF handle per thread," per V18 §Threading; this lock is an explicit opt-in mechanism layered on top, not a replacement for that rule).

Return value. True if IPDF is valid; False otherwise.

C# (P/Invoke)

[return: MarshalAs(UnmanagedType.Bool)]