Infrastructure Software

Hi,

I am interested in extended attribute implementation details on TMPFS and NFS file systems.
'fsattr' man contains following:

" Conceptually, the attribute model is fully general. Extended
attributes can be any type of file (doors, links, direc-
tories, and so forth) and can even have their own attributes
(fully recursive). As a result, the attributes associated
with a file could be an arbitrarily deep directory hierarchy
where each attribute could have an equally complex attribute
tree associated with it. Not all implementations are able
to, or want to, support the full model. Implementation are
therefore permitted to reject operations that are not sup-
ported. >>>>For example, the implementation for the UFS file
system allows only regular files as attributes (for example,
no sub-directories) and rejects attempts to place attributes
on attributes.<<<<
"

Rest of man pages have no information about this feature. I would like to know:
-Is there any kind of limitation on TMPFS or NFS similar to UFS (what can be attribute)?
-What are allowed attribute types on TMPFS or NFS?
-What is point of extended attributes on 'tmpfs'?
-What is maximum number of extended attributes (if exist)?

Does anyone know where to find documentation?