pdfSetFieldBorderStyle

int32_t __stdcall pdfGetFieldBorderStyle(PPDF IPDF, uint32_t AField);
BOOL32 __stdcall pdfSetFieldBorderStyle(PPDF IPDF, uint32_t AField, int32_t Style);
double __stdcall pdfGetFieldBorderWidth(PPDF IPDF, uint32_t AField);
BOOL32 __stdcall pdfSetFieldBorderWidth(PPDF IPDF, uint32_t AField, double LineWidth);

function pdfGetFieldBorderStyle(const IPDF: PPDF; AField: Cardinal): Integer; stdcall;
function pdfSetFieldBorderStyle(const IPDF: PPDF; AField: Cardinal; Style: Integer): LongBool; stdcall;
function pdfGetFieldBorderWidth(const IPDF: PPDF; AField: Cardinal): Double; stdcall;
function pdfSetFieldBorderWidth(const IPDF: PPDF; AField: Cardinal; LineWidth: Double): LongBool; stdcall;

Purpose. Get/set a specific field's /BS /S border style and /BS /W border width — both explicit-handle, unlike the color triad above.

Return value. Getters: the value; 0/0.0 if AField doesn't resolve. Setters: True on success.

C# (P/Invoke)

[return: MarshalAs(UnmanagedType.Bool)]