Entity references in path/transform data

Some clarification please.  Is it considered valid to embed entity
references within path and transform data?   I'm thinking along the
following lines:

<!ENTITY line "L 200 200">
<!ENTITY trans "translate(100, 200)">

<svg width="640" height="480">
	<g transform = "&trans; rotate(30)">
	<path d = "M 400 400 &line; M 300 300 &line; z"/>
	</g>
</svg>

Can anyone point me to the relevant parts of the SVG/DOM specs that either
preclude or sanction these types of constructs?  Failing that, can the
working group clarify whether this use of entity references is legal?

S.