Answer: Need to create bulk bookmarks in Microsoft Word using PowerShell with large documents

Can you test my code first? If this VBA code runs the way you want it to, let's try to rewrite it to PowerSheel:

Sub Need_to_create_bulk_bookmarks_in_Microsoft_Word_using_PowerShell_with_large_documents()
    Dim p As Word.Paragraph, rng As Word.Range, d As Word.Document, a As Word.Range, str As String, rngBookmark As Range, ur As UndoRecord, s As