Nested lists and label-width

[Andrea Mattioli <aldaris@jumpy.it>]

Hi,
I have many nested ordered lists with the attribute inheritnum set to 
"inherit".
The problem is that the space for the label doesn't grow with the 
deep of the list so at a certain point

- the label's numbers of the <listitem> overlaps its text (using FOP)
or
- the label's numbers of the <listitem> are compressed in the 
available space (using XEP)

Is there a way to specify that the label space should be proportional 
to the length of the label,
for example with an attribute or using a processing instruction ?

Thank you,
	Andrea.