Validation Error - no attribute "xmlns:v"

If you are copying and pasting content from another Microsoft program into Expression Web and then try and validate your page, you are likely to get an error message

Error Line 2 column 61: there is no attribute "xmlns:v".

...w3.org/1999/xhtml" dir="ltr" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o=

Screenshot validations error message.
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That is because Expression Web will add the following to your doctype statement

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" dir="ltr" xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office">

If you remove from xmlns to the end (highlighted text), your document should then validate assuming there are no other errors.