Brian, it is inappropriate because the spec says so.
Example of HTML src attribute with img element View this example in a separate browser window
Type of value.
Example of HTML src attribute with frame element
HTML attributes are a modifier of an HTML element type.An attribute either modifies the default functionality of an element type or provides functionality to certain element types unable to … The src attribute instructs the browser where on the server it should look for the image that’s to be presented to the user. Obviously this is not the case, and if you 'href' when your supposed to 'src' your gonna have a bad time. Together with SRCTec, our manufacturing subsidiary, we are redefining possible through innovation in science, technology and information — working for the best solution, not the bottom line. Example of HTML src attribute with frame element HTML 4.01 strict, HTML 4.01 transitional when used with img, input and script elements.