Syntax of xmltable function

Hi

I am working on xmltable function. This function is used for simple data
extraction from XML documents. In this moment I am working on prototype's
parser.

The SQL/XML syntax is:

XMLTABLE (
xmlquery
PASSING xmldocument
[COLUMNS columns_list] )

columns_list := column_list ',' colname

colname := colname datatype [DEFAULT value] [PATH text]

The DEFAULT clause is before PATH clause.

I am able to implement the default clause with c_expr - It is enough for
almost all usage.

What is question?

A Oracle db uses little bit different syntax - the DEFAULT and PATH clause
are in different order. This is little bit better for Postgres too - now I
can use a_expr in DEFAULT clause - what can be little bit better for other
than text types.

What should be preferrable? ANSI SQL syntax or Oracle syntax? This is not
often task - I didn't find any example with DEFAULT clause for Oracle.

DB2 and Sybase uses exact ANSI SQL syntax.

Regards

Pavel