Reference manual bug

[Mikael Djurfeldt]

The node "C Port Interface" in the reference manual contains the
following paragraph:

  Port basics
-----------  
  
  There are two main data structures.  A port type object (ptob) is of
  type `scm_ptob_descriptor'.  A port instance is of type `scm_port'.
  Given an `SCM' variable which points to a port, the corresponding C
  port object can be obtained using the `SCM_PTAB_ENTRY' macro.  The ptob
  can be obtained by using `SCM_PTOBNUM' to give an index into the
  `scm_ptobs' global array.

I think I can call me a "Guile veteran".  However, I have to confess
that I hardly understand this text.

There are too many concept labels here: "port type object", "ptob",
"port type object type", "scm_ptob_descriptor", "port instance", "port
instance type", "scm_port", "port" and "port object".

It seems like one can use fewer labels.  For example, why introduce
the notion of a port type object at all?  Why not just call it a
scm_ptob_descriptor?

(Or, maybe we should just rename scm_ptob_decriptor into scm_port_type
in the source?  If so, we should probably rename scm_ptobs to
scm_port_types.)