type casting bpchar

Dear all,

I want to alter a table by creating a similar temporary table with my
modifications and inserting the values of the old table, but I get the
error message:

ERROR:  Attribute 'tag' is of type '_bpchar' but expression is of type 'bpchar'       You will need to rewrite or cast
theexpression
 

Question is how do I do this, because when I write the offending value
as tag::_bpchar, I get:

ERROR:  Cannot cast type 'bpchar' to '_bpchar'

This seems to be a dilemma which I don't know how to solve. I hope
someone can help me.

Greetings,
joachim

--          Dr. Joachim Trinkwitz              email: jtr@uni-bonn.de        Germanistisches Seminar             phone:
0228-737565
Rheinische Friedrich-Wilhelms-Universitaet   fax:   0228-737479     Am Hof 1d, 53113 Bonn, Germany         web:
http://www.germanistik.uni-bonn.de/jtr/