PHP: SUBMIT Type vs IMAGE Type

I have noticed that when using a SUBMIT type its name attribute gets passed via POST , while an IMAGE type button do not have this data sent, can any one clear this up 开发者_C百科for me? In both instances the NAME attribute is present at HTML level, but only the SUMBIT type has the NAME sent via POST....is this right?

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From http://www.w3.org/TR/html401/interact/forms.html#h-17.4:

image

(snip)

When a pointing device is used to click on the image, the form is submitted and the click coordinates passed to the server. The x value is measured in pixels from the left of the image, and the y value in pixels from the top of the image. The submitted data includes name.x=x-value and name.y=y-value where "name" is the value of the name attribute, and x-value and y-value are the x and y coordinate values, respectively.

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When you submit via image, it sends the coordinates of where the image was clicked, so if the image is named image you'll have the POST parameters image_x and image_y