When a PDF file is opened in Adobe Acrobat Reader, it will lock the file so no other process can write to the file while it is opened. Use this property to load a PdfDocument from the PDF file in a read-only mode while it is still opened in Adobe Acrobat Reader.
Also, if you want to open a PDF file in Adobe Acrobat Reader while the PdfDocument is loaded from the PDF file and before it is closed, then use this property to load a PdfDocument from a PDF file in a read-only mode.
Note that loading a PdfDocument from a PDF file in a read-only mode (without acquiring an exclusive write lock on the file) might lead to unpredictable behavior if the file is simultaneously changed by another process because the PDF file is read into memory incrementally and lazily. To prevent the unpredictable behavior at the expense of performance, use Load method to read the entire PDF file into memory.
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