J.P. wrote:
MS Office 2002 & 2003
Selecting text and formatting Bold, Underline or Italics, causes the
whole document to adopt the format.
Place cursor anywhere on the page and click 'undo clear' will result
in clearing all of the format except forthe original selected line.

See http://word.mvps.org/FAQs/Formatting...eformatted.htm.

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Regards,
Jay Freedman
Microsoft Word MVP FAQ: http://word.mvps.org