ParameterMetaData getPrecision() always zero?

Driver: postgresql-8.4-701.jdbc4
Server: 8.4
OS: Mac OSX

<snip>
ParameterMetaData m = stat.getParameterMetaData( );

if ( null != m ) {

int colWidth = m.getPrecision( parameterIndex );

// colWidth == 0 means 'not applicable'
if ( colWidth > 0 ) {
<snip>

I have the same behaviour with many different tables.

For varchar columns I would expect to get the maximum column width. So 8 for a varchar(8).

I always get zero as a result.

I get non zero values from H2 and Derby drivers.

Is this a bug or have I missed something?

TIA

Simon Temple