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Currently, when the "Transliterate file names during upload." checkbox is ticked at admin/settings/file-system, all whitespace characters will be replaced by an underline (_) character. Can we please have a checkbox that allows unticking that behaviour? More than one spaces side by side should still be reduced to a single one, but if you are using "pretty" self-explaining filenames for files that are attached to a node, spaces look prettier than underlines, so it would be nice NOT to force replacing by an underline.