It seems that this particular mistake (a 'target' attribute in strict mode) is so common that it's the example the validator uses: > This error is often caused

It seems that this particular mistake (a 'target' attribute in strict mode) is so common that it's the example the validator uses: > This error is often caused by incorrect use of the "Strict" document type with a document that uses frames (e.g. you must use the "Transitional" document type to get the "target" attribute)