Trying to bring PEP up to date with discussions on mailing list. I hope I

have not misinterpreted the conclusions.
* dialect argument is now either a string to identify one of the internally
  defined parameter sets, otherwise it is an object which contains
  attributes which correspond to the parameter set.
* Altered set_dialect() to take dialect name and dialect object.
* Altered get_dialect() to take dialect name and return dialect object.
* Fleshed out formatting parameters, adding escapechar, lineterminator,
  quoting.

pep-0305.txt

@@ -105,19 +105,42 @@ Dialects
 --------
 
 Readers and writers support a dialect argument which is just a
-convenient (string) handle on a group of lower level parameters.
+convenient handle on a group of lower level parameters.
+
+When dialect is a string it identifies one of the dialect which is
+known to the module, otherwise it is processed as a dialect class as
+described below.
+ 
 Dialects will generally be named after applications or organizations
 which define specific sets of format constraints.  The initial dialect
-is "excel2000", which describes the format constraints of Excel 2000's
+is excel2000, which describes the format constraints of Excel 2000's
 CSV format.  Another possible dialect (used here only as an example)
 might be "gnumeric".
 
+Dialects are implemented as attribute only classes to enable user to
+construct variant dialects by subclassing.  The excel2000 dialect is
+implemented as follows::
+
+    class excel2000:
+        quotechar = '"'
+        delimiter = ','
+        escapechar = None
+        skipinitialspace = False
+        lineterminator = '\r\n'
+        quoting = 'minimal'
+
+An excel tab separated dialect can then be defined in user code as
+follows::
+
+    class exceltsv(csv.excel2000):
+        delimiter = '\t'
+
 Two functions are defined in the API to set and retrieve dialects::
 
-    set_dialect(dialect, pdict)
+    set_dialect(name, dialect)
-    pdict = get_dialect(dialect)
+    dialect = get_dialect(name)
 
-The pdict parameter is a dictionary whose keys are the names the
+The dialect parameter is a class or instance whose attributes are the
 formatting parameters defined in the next section.
 
 
@@ -135,6 +158,9 @@ for the set_dialect() and get_dialect() module functions.
 - delimiter specifies a one-character string to use as the field
   separator.  It defaults to ','.
 
+- escapechar specifies a one character string used to escape the
+  delimiter when quotechar is set to None.
+
 - skipinitialspace specifies how to interpret whitespace which
   immediately follows a delimiter.  It defaults to False, which means
   that whitespace immediate following a delimiter is part of the
@@ -143,6 +169,17 @@ for the set_dialect() and get_dialect() module functions.
 - lineterminator specifies the character sequence which should
   terminate rows.
 
+- quoting controls when quotes should be generated by the
+  writer.
+
+    "minimal" means only when required, for example, when a field
+    contains either the quotechar or the delimiter
+
+    "always" means that quotes are always placed around fields.
+
+    "nonnumeric" means that quotes are always placed around fields
+    which contain characters other than [+-0-9.].
+
 ... XXX More to come XXX ...
 
 When processing a dialect setting and one or more of the other