HTML Reference : HTML Elements :
BUTTON

Creates a button whose contents are rich html. When examining the DTD information, notice that many elements are excluded from being contained within a button (the red text).
Attribute Information

accesskey - IE4, IE5

disabled - IE4, IE5

name - IE4, IE5

onblur - IE4, IE5

onfocus - IE4, IE5

datafld - IE4, IE5 (reserved)   CDATA

dataformatas - IE4, IE5 (reserved)   html (IE4, IE5) plaintext (IE4, IE5)

datasrc - IE4, IE5 (reserved)

tabindex - IE4, IE5

type - IE4, IE5   button (IE4, IE5) reset (IE4, IE5) submit (IE4, IE5)

value - IE4, IE5

DTD Information
The DTD defines the set of elements that can be properly contained within the element.

A FIELDSET flow block ADDRESS BLOCKQUOTE CENTER DIV DL FIELDSET FORM heading H1 H2 H3 H4 H5 H6 HR list DIR MENU OL UL MULTICOL NOFRAMES NOSCRIPT P preformatted PRE TABLE inline fontStyle B BIG I S SMALL STRIKE TT U formctrl BUTTON HTMLAREA INPUT LABEL SELECT TEXTAREA phrase ABBR ACRONYM CITE CODE DFN EM KBD SAMP STRONG VAR special A APPLET BASEFONT BDO BR FONT IFRAME IMG MAP OBJECT Q SCRIPT SPAN SUB SUP FORM formctrl BUTTON HTMLAREA INPUT LABEL SELECT TEXTAREA IFRAME ISINDEX