The only file type the Writer app can open is FDX, the format used by Final Draft 9 / 8. It does not open FDR (Final Draft 7 / 6 / 5), RTF, DOC, TXT, HTML or PDF files.
Some other screenwriting programs can save as FDX, but these files are not written in genuine Final Draft FDX and the scripts may not look or behave as expected when opened in Final Draft 9 / 8 or Final Draft Mobile apps.
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